Migrate Collective security deposit payments

Hi,

We are in the process of migrating our open balances and interest charges on customer accounts. For the customer security deposits, we need to migrate the security request as well as their payments.

In the case of collective accounts, we initially created request at the child level. This created a statistical document at the parent level. However, when we try to apply payment, should we provide the child request number or the parent?

When we try to provide the collective account, system is saying there are no open items for the account. We are using the standard collective clearing variant '20S' and don't have any custom one build in the system. Do we need to create a new clearing variant for security deposit payment migration on collective accounts?

Please help me with the steps to migrate the security deposit payments on collective accounts.

Regards,

Santosh.