I recently received some asemblies. These are models of structures that must be fasten to the deck of a vessel. the models came with the lashings. I brought the deck from a dwg and then brought the first structure. I put it in place, then the next step was to move the lashings to make sure they are connected to strong points. I tried with mate but it makes the whole structure move. I thought the cause could be other mates acting or that every subassembly was fixed. I checked the mates field and there is not nothing displayed so maybe the mates came somehow internally (maybe the model was generated in another software?) I tried to unfix the subassemblies of the structure, in this case the lashings to be able to move them, but I did not managed, I checked online and one guy recommended to make the subassemly flexible. I tried with that option but there is a warning saying "File name entered was invalid, not found, locked or of an incompatible type". So it basically seems like the parts/ subassemblies can not be unfixed from the assembly, but I need to move those lashings. What can I do?  I don't get what could be the problem. Thanks in advance!