Option 1: Put your Quotes data and Policy data into a single table. Convert a "Quote" into a "Policy" either by changing a field's value or by duplicating the record and then updating the copy to show ti as a policy.
Option 2: Make another TO of Clients and link it to Quotes exactly like you do Clients to Policies. When a quote needs to become a policy, simply create a new policy record and give it the same ClientID as the quote--something that can be scripted.
The second option eliminates any need for double entry of client data as does option 1, but if there is a lot of data in a quote that also needs to be in the new policy record, moving that data from a record in quotes to a new record in policies is a more complex process, but one that can be scripted so that all the user does is click a button.