Using API connecting 2 records via ID

Hello,

i'm looking for a solution for my problem.

We have 2 Modules and we'd like to connect/relationship between 2 records.

1 record in module A

1 record in module B

 We'd like to use the sugar ID (Record ID) as indicator.

Some Ideas?

Looked through the documentation and found nothin clear and similar.

Probably quite simple

Thanks!