Migration from JBPM5 to JBPM latest version 6 or 7

For changing the sensitivity to Sev-2, because, we are getting lots of process instances which are getting stuck at different nodes because of version changes. As per last discussion with Red hat support manager, in different given solution for the problem, we decided to migrate to JBPM6.

For same we are trying to make a POC to get this migration activity ASAP. As we have customized the core JBPM5 framework according to our Requirement.

Agenda of Discussion:-
1. What is the best way to Migrate to JBPM6 according to current running PROD Env?
2. Loading bpmn/packages and creating kbase/kbases using code in JBPM6/JBPM7 which one is preferable
3. Maintain different version of bpmn and running all version in parallel in embedded mode.
4. Exact implementation of the solution provided by you for above question with some reference examples

It would be really great if we could talk about this by today EOD, so that at least we can complete this POC by Monday, as we are running short of time.