Dear Fernando Alvarez,
Does your use case require access to multiple schemas during the same call to the AMDP method at runtime or is it the case that during a method call you would access only one specific schema?
If later is the case you might want to check the possibility of using secondary database connections from AMDP. From NW AS ABAP 7.4 SP08 onwards AMDP methods support the usage of secondary database connections(maintained from DBACOCKPIT).
You can find more information from this help documentation.
Additionally you can refer to the following blog as well.
Please let us know if this information is helpful to identify the right solution for your use case.
Best regards
Sundar