I saw a topic on someones n64 portable. They said they soldered two ram chip from two expansion packs onto the n64 mother board and solders the expansion card to the board itself. I was wondering, say you two ram chips and soldered them to the board and got a third ram expansion pack and soldering that to the board with its ram chips still on it. Would that up the RAM of the N64 further or would the n64 still just read the just the one set of RAM chips on the board?

Even if games would still boot, they wouldn't address the additional RAM, so there would be no apparent difference in performance.

SO would it work if I just solders the RAM chips to the board and soldered the Expansion pack PCB to the Spot where the original exp. slot was?

If you soldered the two 4MB chips to the mainboard, all you'd need to do is add the jumper pak, not another expansion pak.