LOD = Level of Detail
Connecting parts using LOD task, the parts could assume different positions and/or suppressing parts as per you request the LOD. You link what you need and all changes are done only swaping the LODs. Ex:
Assembling with A B C parts
LOD 1 = A mating parallel B with 20mm far from each. C suppressed
LOD 2 = A mating parallel C with 30mm far from each. B suppressed
LOD 3 = C mating concentrical B with 10mm far from each. A suppressed
Resume: You put all parts you need in an assembly, raise all constraints, raise the LODs, only turn it on/off parts and constrains per LOD created, and it changes automatically