Merging two scenery files

Howdy folks,
Does anyone in here know how to merge two scenery files?
I'm specifically looking at merging Iain Gallacher's Duxford Scenery (here) and Thomas Moger's Stratic F-15 Display (here).
I've tried different things but I can't figure it out. Could it have something to do with the position of the plane? It might be covered by the hangar but how do I check this?
If anyone knows the answer or has any tips (or tools) please let me know.
Thanks!
Harold
Does anyone in here know how to merge two scenery files?
I'm specifically looking at merging Iain Gallacher's Duxford Scenery (here) and Thomas Moger's Stratic F-15 Display (here).
I've tried different things but I can't figure it out. Could it have something to do with the position of the plane? It might be covered by the hangar but how do I check this?
If anyone knows the answer or has any tips (or tools) please let me know.
Thanks!
Harold