Yes, you only need to redefine [or, relocate] the primary part of the pattern within the assembly, then redefine the pattern sketch. [you may need to delete some of the existing constraints, in order to reposition it]
If you want to use a different part instead....right click on the part in the pathfinder, go to "More", choose "Replace Part"...then choose the file to replace with...relationships will need to be redefined, and the pattern should update to use this part also. [otherwise, right click on the "Pattern" in the pathfinder, and choose "Edit", then select the new target primary part.
Sean Cresswell Design Manager Streetscape Limited Solid Edge ST9 [MP8] Classic [x2 seats] Windows 10