Answers below....
I have the question if it is possible to start one of the available MPL programs out there if you already have followed an integrated program and thus already hold a MEP CPL IR License?
It is an ab initio programme, not designed for licence holders especially if they already hold professional licences.
Asking the airline you have a head start in the MPL program, they might accept you in doing their program?
No, you do not have a head start. Each MPL syllabus is unique to the Operator and no account will be given for previous experience.
Perhaps begging them to say you have the ability to quickly finish their MPL program because groundschool is already completed, some needed flying skills are already completed, so overall cost to become at their MPL level is way cheaper than a starting MPL'er which mean cost reduction by their recruitment department?
Is it possible?
There is no credit for previous flying at all. The technical ground school exams can be accepted but all cadet programmes worth their salt will require you to at least do the mock (internal college) exams again. So... No again.
Or can one cancel their current license and start again fresh with an MPL program?
No. Your records will show what you have/have not achieved.
Or just don't mention about already having a license while going through the selection process of the MPL program?
(because of the benefit of the job perspective incl. with the MPL program...)
Being dishonest will get you in trouble sooner or later....
Any advice, tips, tricks, or experiences by someone who might have done such steps,,,much appreciated!
If you already hold a ME CPL/IR then keep plugging away to get experience and that first job. There is no shortcut, the MPL is not for you.