Never having read the books I know nohing about them obvioulsy but the whole concept of doing crossovers on TV and cinema sounRAB terrible.
How can it be guaranteed that the TV series will be shown to coincide with the film.
The TV channels will show it as and when they like and at whichever time they like. They may sit on it waitng for the next film to come out then show it which is great if you manage to see it all before the film comes out, if you don't you miss seeing it in the ciinema and have to see the film on DVD. If it's on ITV it could get pulled at any time to make way for some football match. If the ratings are bad it could get axed completely or get switched to a death slot.
What is an smaller channel like Scyfy or Bravo get it? People may not be able to get access to see the series and so when the next film comes along they won't have a clue, unless they just read spoilers and hope they don't find out anything that happens after this second film.
What is no channel in a countty takes the series but the films are shown in that country?
It may be possible to o crossovers but it does sound like it could cause more problems for people than it's worth.