How to make 3d max not hit groups in UV Editor?

Question

3D

Hi guys. I know that there are mostly progers here, but I believe that there are people who can help me. There is 3d max 2017.
There is, say, a room that I want to make with one texture for the game. It has, for example, five different machines, and one of them has 10 bolts. I Unwrap UVW the table, where I put these bolts one on top of the other and generally arrange the table layout in every possible way. Then so same the second and all the rest. Then I want to bring the room to one texture and apply a second UnwrapUVW to all elements. And at this moment I can’t explode the elements in any way so that the bolts do not break into separate entities. Neither FlattenMapping nor Arrange Elements. I again have 10 separate bolts, which again need to be merged. And if the bolts on each of the tables are different, then this is quite problematic.
How do professionals usually do it? Maybe in some other way they bring objects into one texture (I generally would like one type of object to be kind of together, and not scattered), I tried to use groups, but it ignores them and still beats.