How to weld an unanchored part to an anchored one?

I tried welding a part that was not anchored to a moving anchored part (because it was animated using tweens) but it did not follow it, it didn't move at all. Is there a way to fix this and if not is there an alternative?

go the the part you are trying to weld, then add a weld to it then press on the weld and set the parent to the main object (the anchored part) and set the child to the un anchored part