See the following thread
I’ve got two v1 hubs at two locations and have worked this issue with support for awhile. Currently its just not possible without having 1 location per SmartThings Account. Now what I will probably end up doing is have one location utilize native echo integration, and another use a hue emulator method. I suspect that should work fine since there are two distinct OAUTH smart apps involved there (1. echo and 2. Custom REST endpoint) but I’ve yet to reconfigure the emulator solution I had setup prior to native echo integration. keep in mind this will (should) work for echo but not for other integrations like IFTTT, SharpTools, etc… For those I simply have to pick a hub whose devices I want to interact with at any given time.
As far as v2 goes, if having any of these services for both of your hubs right now is important and worth the hassle of having two smartthings accounts then I suggest you combine the creation of the new account with the migration of devices to v2. Like the v2 migration, the implementation of getting a new account requires a device tear down/re-setup. Piggy backing that process onto the migration’s tear down would be best. If you can wait then hopefully enough people getting v2s will become multi-hub accounts and it will drive prioritization of a resolution to this unanticipated limitation.