Upgrade HP DP 7.03 with very old clients

I need advice.
There is a HP DP 7.03, which da clients 5.5, 6.11, 6.2, 7.0. We are planning to move to HP DP 9.
Most of the clients can be upgraded to 7.0 and then to 9.0. However, there are several systems with old clients, for example AIX 5.3 with c DP DA 5.5 and 6.1. This version formally is not  supported HP DP 9.0 (Platform_Integrtn_SptMtx_DP9.00) system. Also, there is no way to modify or update these legacy systems due to special software.
Question: what to do? Can the scheme, when the Cell is version 9.0, and one of the MEDIA server - version 7.0 and will only serve these ancient clients? Or is it a very strict ban and update Cell to 9.0 is not possible?
Thank you