Can some one give please give me an overview of  how to work with Multibody sheet metal parts one or 2 parts is ok

But  at what stage do you put the first  part file in to an assembly then add other additional part file to the assembly?

I assume a small simple sheet metal part  made from just a few bodies it can all be in one part file is this correct?

Then  if you have other items that are not Sheet metal ie just solid  parts or weldments or something else   ie not sheet metal What is the best way  to you set this up

Can't find a strategy/ over view

Thanks

Andrew