How to Upgrade EBS 12.1.3 (Which AP nodes in different kinds of platforms) to 12.2.7

Hi Experts,

Could you please share some advice on this ?

[EBS 12.1.3 configuration]

    Customer have an un-supported EBS 12.1.3 configuration as following :

        one node database on Sparc

        two node application one on Sparc second one installed on Linux as DMZ    -----Different platforms of AP Nodes.

    Now they plan to upgrade from 12.1.3 to 12.2.7, issue here is they will upgrade application in SPRAC but how they can upgrade it in Linux since they are using same Database .

[Query]

    The issue here that we handle upgrade project from 12.1.3 to 12.2.7

    and DMZ configure in linux and Application in Solaris. this setup before 7 years and i dont know who implemented