Hello
Will they be able to upgrade directly from SRM 5.0 on NW7.0 to SRM 7.0 on NW 7.3 ?
Have a look at these SAP note
Note 1371998 - Consulting Service: Upgrade SRM Server
It is possible and here is the evidence:
KBA 1781127 - Upgrade Issues from SRM 5.0 to SRM 7.0 and on
Regards
RB