SAPUserInSAPRole to UserInRole - Mapping: Building Schema Classes for Target System Side

In my SAP/3 Syncproject, i have a mapping between SAPUserInSAPRole and UserInRole.

I built left hand side (One Identity manager side) some schema classes to limit the records that may be matched to records on the right side.

The Schema Classes use filters like this one here for the left side in the system filter of the schema class:

1=1
and UID SAPUser in
(
    select UID_SAPUser
    from SAPUser
    where
    1=1
    -- Primary Accounts
    and not isnull(UID_SAPSecPol,'') in (select LIID_SAPSecPol from SAPSecPol where Ident_SecPol 'TECHNISCHE USER' )
    -- keine Testuser
    and not UID_SAPUser in (select UID SAPUser fron SAPUser where UID_SAPGrpDefau1t in (select UID_SAPGrp from SAPGrp where Name like
    '%test%')
)

The same thing, i want to do on the right side (SAP target system side)

There i have the "UserInRole" Table.

To build a schema class, where all right side records meet certain conditions, i want to create some virtual attributes that deliver values, i can build a filter on. For that, i need virtual linked attributes, because the filter uses information from linked records (user for userinrole)

Unfortunatley, at a userinrole record right side there is only a UNAME that i can use to navigate to the corresponding USER Record and only choose userinrole-Records, where the linked user meets certain conditions.

I don't think that a "key resolution" virtual attribute does the trick, because as i understand "Key resolution" you need some kind of real foreign key contruct to navigate along.

If i try anyway to use key resolution and check the result in target system browser and choose a record, sync editor hangs up and never returns.

Is there another to achieve what i want?

I cannot imagine, that one identity does not have something in his toolbox to achieve what is needed here.