Playing an Exile
Playing in exile is something I think will be more popular in multiplayer than single player, because you are limiting yourself quite a bit, but for those who like a challenge we wanted to make sure it was possible and give you some of these advantages as well!
If your host is an AI it will be trying to be helpful in this case by passing over control of veteran divisions arriving. Exile Commanders will also be under your control. Because some exiles will have no land at all you will likely need to depend on the master for lend lease of equipment to arm your divisions with. If you are totally landless you will be getting a trickle of manpower based on your Legitimacy as well (Poland is likely in this position while Netherlands or France wouldn’t necessarily be). When you are an exiled nation you can keep track of your legitimacy on the country screen as well as bring up the more detailed view like the host nation can:

Exiled nations also come with several new decisions to help them grow and to celebrate their achievements. We also plan for exiles of nations that don't fall normally, like Czechoslovakia to come into existence from decisions.

Imperial Conferences
Hi! Bratyn here. In the thread for the British Focus Tree dev diary a lot of community feedback pointed out the glaring lack of the Imperial Conference as a potential ahistorical path. As I already mentioned in certain threads, this has now been rectified

I have rearranged the Dominions development branch of the Reinforce the Empire path, and added three new focuses. After having developed Canada, South Africa, Australia, and New Zealand, it is now possible to kick off the [insertcurrentyearhere] Imperial Conference. Doing so will send a notification event to all parties involved (including yourself), which then activates the Imperial Conference decisions.

This text has since been adjusted to properly locate the Conference in London!
However! Note that this conference will only last for 60 days, and so even though the “Hold the Imperial Conference” focus grants 120 political power, you should be prepared by having a sizeable amount of political power saved up in order to push through the motions you want during this timeframe. Considering the likelihood of the Dominions agreeing to your motions depends to a large degree on their opinion of you, you may also want to have prepared by improving relations with them before you kick off the conference, as you will likely not have time for this in the 60 days you are given. Finally, to make opinion actually matter, all positive opinions throughout the game have been cut in half, and on top of this you get a -100 opinion modifier with all your Dominions (and India) for the duration of the conference. This allows us to use the 0-100 range of opinion to calculate AI likelihood of accepting your proposals.

The possible motions to make are the following:
Imperial Defense: Each Dominion that accepts gains a 10% production bonus for factories and dockyards for 365 days. Accepting costs them 25 political power. For each Dominion that accepts, the UK gets 3% production bonus for factories and dockyards (for a grand total of 15% bonus max, if all 5 accept) for 365 days.
Imperial Trade: Each Dominion that accepts is flipped to the Free Trade law (this making a larger amount of resources available for export), and the UK gets a +50 trade relations opinion modifier with them.
Imperial Economy: Each Dominion that accepts gains a 10% construction speed bonus to civilian and military factories, and dockyards, for 365 days. Accepting costs them 25 political power. For each Dominion that accepts, the UK gets 3% construction speed bonus to civilian and military factories, and dockyards (for a grand total of 15% bonus max, if all 5 accept) for 365 days.
Appeasement: Only available if the UK is not at war. Each Dominion that accepts gains 10% war support. Accepting costs them 25 political power. For each Dominion that accepts, the UK gets 3% war support.
In addition, Dominions that accept the previous four motions will also get 10 opinion with the UK per motion they accepted. This gives you a way to improve opinion other than simply improving relations. Each motion costs 50 political power to start. Of course, note that all values are subject to change based on testing.

WIP event picture!
Each motion kicks off with a starting event for the UK, where the player can choose whether to roll the dice solely based on the Dominions’ opinion, or to invest various degrees of political power (currently 25 and 50) to influence the outcome. Influencing them will double and triple (respectively) the chance of them saying yes, but the only thing that will absolutely guarantee it is if they have 100 opinion with you.

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Finally, there is the Imperial Federation motion. This one is a bit different from the previous four, because it will not have effect unless at least Canada, South Africa, Australia, and New Zealand unanimously accept the motion. This costs 100 political power to start.

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India is a bit of a special case. They were not a Dominion, and so if you want their support you will have to first make them one. This is where the new “Indian Autonomy” focus comes in. Taking this will make the Raj a dominion, and also give them +0.5 autonomy gain for 2 years. If you do this before the Imperial Federation, the Raj may (following the same opinion restrictions as the other Dominions) accept the Federation proposal. If you do not grant them autonomy before triggering the Conference, they will always reject it.

WIP event pictures!
If all five Dominions accepted, they then all receive a national spirit that reduces Autonomy by -3 per day. You will manually have to pay the PP to reduce their Autonomy levels all the way down to Integrated Puppet (and these TfV Autonomy levels have therefore been unlocked for MtG!), and once all of them are that Autonomy level, you can take the “Imperial Federation” focus. If India did NOT accept for whatever reason, but all other Dominions did, you can elect to either cancel the plans, or push through with the remaining Dominions and give independence for India. The reason for making this require a long process of autonomy reduction is to illustrate that integration is a long-term process, as well as to make this be a difficult (or at least slow) thing to achieve, due to how powerful it is. The idea is that it should only be possible to get towards the mid-late game. Currently, this takes roughly 3 years. Of course, again note that all values are subject to change based on testing, and especially the speed at which you can integrate them may well change (if anything, likely to be adjusted so that it can be done more quickly).

WIP event picture