Hi @aragot,
There is a concept of a cloudId which ties a group of tenants of different product types together. At one point the cloudId was going to be added to the installation payload, but there was some controversy within Atlassian about the exact semantics of cloudId and the plans never went ahead.
The relevant issue is AC-2379, but this has limited visibility. This is the only way I know of to reliably associate tenants without some kind of manual user assistance.
You may also be interested in the following article: Relationship between cloud id and client key
Regards,
Dugald