ESS EHP5 - using old services

Hi experts,

We are on EHP4 and we are about to start upgrade to EHP5 and we are live for multiple countries so we will have a lot of adjustments to do. Is it possible to use old WD JAVA services after upgrading to EHP5?

I mean, we want to reduce to the minimum time of upgrade (avoiding a large period of different versions on the landscape DEV-QUA-PRO) so we were thinking on upgrading EHP5 using Time Management (EHP5) services only and then upgrade Personal Administration services (after go-live of EHP5, untill there we were thinking about using the old services in WD JAVA). We are using TM, PA and FITV.

Thanks in advance!

Regards,

AS