It is possible and I have both come across this and been asked to do this by Clients in the contracts that I have prepared, although it does take some minor redrafting of the Contract Data text.
If the retention secondary option is specified, the important thing is to be clear about when the final retention is paid back i.e. which defects date it applies to.
If the retention secondary option is specified, the important thing is to be clear about when the final retention is paid back i.e. which defects date it applies to.