I have a modular house upstate New York which is 9 years old. The ceiling keeps cracking in the same area where the 2 parts of the house join together.
Contacted manufacturer and was told that I should cut out a section of sheetrock
Of the ceiling and have a new piece that I'm inserting being 2 feet each side of the main beam. Did this and still keeps cracking in the same area. I keep the house at 40 degrees when not in use. Told this might be the problem. I took out a part of the living room wall to make the room bigger. Can this also be a part of the problem. Thanks for your help in this matter.

The part of the house you are dealing with is under tension. Does your ceiling sheet span two sections of the house. Not sure why the house is in two contiguous sections, is it on a slope? You may need to settle for a less seamless join where the join is covered by a "cornice" or cover strip attached to only one section of the house