Answer
It is not necessary to maintain sequence in the Qadhaa Salaats as the normal daily five Salaats. Missed Salaats may be performed in any order. However, if a person is a Saahib-e-Tartib (person who did not miss more than 5 Salaats in his life), he has to maintain sequence in performing the missed Salaats.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai