As for your original question:

If you get the right person it should be possible to have your luggage checked through to your final destination, regardless of the two different tickets. However there is no guarantee to this and so you have at least the possibility that they won't do it.

You fallback scenario for this will IMO not work out: Another person checking in your luggage is a no go. But he might be able to checkin this luggage onto his ticket if he has enough allowance or holds status with SU or skyteam.

Did you think about sending your luggage via air cargo or via parcel service? It might be not so expensive and you then have a working solution instead of something that potentially provides problems.