Linking Multiple Alarm.com Accounts Serviced By Different Providers

I have a new Alarm.com account with Surety for a newly-purchased home. I also have an older, pre-existing Alarm.com account with another provider, for a house that I plan to sell shortly.

For the period of time that I have to deal with both properties, I am interested in ADC’s ability to link accounts, which I found under Settings | Login Information | Link a System, but wanted to understand a few things properly before plowing ahead and potentially doing something that cannot be easily undone.

Thus, some questions:
1.) After ADC accounts are linked, is there a means for unlinking them (from the Surety end, or otherwise)?
2.) Given my plans to sell the house with the non-Surety system, is my understanding correct that it would make more sense to link TO that other account FROM my Surety-based account?
3.) Would there be any issues with linking separate ADC accounts that are serviced by different providers?
4.) Does the mobile app (Android) take advantage of the account linking, and allow interacting with both systems at properties, without having to play around with logging in/out?

1.) After ADC accounts are linked, is there a means for unlinking them (from the Surety end, or otherwise)?

Yes, you can add and remove Alarm.com Multi-System Access from your account while logged into ADC under Settings > Login Info > Linked Systems.

Given my plans to sell the house with the non-Surety system, is my understanding correct that it would make more sense to link TO that other account FROM my Surety-based account?

Yes it would probably be easier to do it this way, though you can delete and recreate Linked systems easily. The account credentials you are logged into when you create the link will be able to access any linked systems, but not vice-versa.

Would there be any issues with linking separate ADC accounts that are serviced by different providers?

Nope, you can link them as normal.

Does the mobile app (Android) take advantage of the account linking, and allow interacting with both systems at properties, without having to play around with logging in/out?

Yes it does. You can tap on the name of the system to swap between them from within the app.