Mapping Lookup Column to number column of another list

Hello SharePoint Team, 

While Migrating to SharePoint on - premise to SharePoint Online we faced many challenges, There was a standard limitation of Lookup column problem is occurred, to overcome we have made a choice columns. Therefore schema got modified and worked.

With the help of power automate imported the data successfully from on premise through excel, but we could not able to manage those auto incremented Id, so we have created a new number column named as (ParentID) to capture those unique auto increment id from older list.

Now those unique ids (ParentID) are mapped with many tables as a foreign key, but lookup column only see the unique auto incremented ID that is default behavior of lookup column . Looking to map lookup column with that ParentID.

Your Suggestion are welcoming here.