Relation between custom fields from diferents CPT

Hello,
I’m creating a CMS for real estate.
I have the following Custom Post Types: Renters and Buildings, and need to reference what Building is a Renter renting.
Solve it using the Advanced Custom Fields plugin – with a relational field I can select an existing Building when editing a Renter.

My problem:
There are commercial Buildings that have several Rooms for rent.
One Room (Child) must be directly connected to a Building (Parent) and both must appear for selection in the Renter registration.

Possible solution:
I can create a CPT for Rooms and manually attach them to a Building, but the registration would be complex and time consuming (multiple screens…)
Except there is a way to edit a Custom Post Type inside another CPT. Any Ideas?
Alternatively, Rooms can be a Custom Field (Repeater) of Building (Custom Post Type), but both (Build and Rooms) should appear when editing Renters (Custom Post Type). Is that possible?

Thank you in advance!