This discussion is none of my business, so I apologise for sticking my nose in, but working for an Anglo-Dutch firm (but with the Dutch in the driving seat) a lot of this sounds horribly familiar, hence my interest.
Can I ask a couple of questions to aid my own understanding?
It sounds that from the VNV concerns the KLMuk pilots are paid less for doing a comparable job - hence the VNV are worried that the concept could be used to provide cheaper pilot labour to operate KLM flights. Is this correct? If it is how about this for a solution:
KLMuk pilots get a contract the same as the other Cityhopper pilots and are given a place on the KLM seniority list comensurate with their pay - VNV wins as the KLM pilots are displaced less than if it was done on joining date; KLMuk pilots win because they get a foot in the door on the main list. They could also offer a 2-3 year fleet freeze on joining the main list (ie the benefits of seniority don't kick in straight away. To join the seniority list a fairly basic Dutch test has to be taken - I would guess that most UK pilots will have picked up enough Dutch to pass this already, but it would show willing.
Whether KLM would go for this I have no idea, but it would appear to give them the opportunity to remove the extra overhead of a UK subsidiary required to comply with TUPE legislation - all depends on the difference in pilot costs between UK and NL pilots. As long as any extra salary costs were covered by losing this overhead then they shouldn't object.
Is the place you live an issue? If you are not already officially NL resident then they may want you to move, but I would think that could be done without actually changing what you do now (ie digs in Amsterdam for stopovers/standbys, but live in UK apart from that). Presumably the concept of commuting pilots is not unusual a la BA.
Presumably this will all come to a head in the not too distant future anyway, as those Fokkers aren't getting any younger.
Another thought - would all the KLMuk pilots joining the VNV make any difference/ Although you would be in a minority, if you were able to be a vocal minority then you would be hard to ignore!
Apologies again for intruding.....