How to replace these deck platform beams?

Hey guys sorry I will get some pics in the morning. The 2nd floor has an outside stair with a 10' or so walkway platform when you come out the door. This platform is supported by 3 wooden 6x6 beams but there are 2 beams which seem to be coming out from the house foundation itself and these 2 beams are rotten mainly on the other ends which rests on iron posts.

I would like to replace those 2 beams but can't figure out how. I have a construction friend but he too doesn't have any idea how to cut off the rotted beam from the side of the house and and also how add a new beam under the platform so I am looking for ideas please?

 

Sounds like they are cantilevered. You would need to build temporary supports for the deck, open up about 12' of the ceiling inside in order to replace them. Can't say much more than that without seeing it.

 

Ok, I just took the pics. As you can see, we have already but the temporary supports in place, now as mentioned is first, how the heck to cut the beam at or inside the edge of the wall?

https://i.postimg.cc/yxmP1WWF/IMG-0104.jpg
https://i.postimg.cc/vZBWj077/IMG-0102.jpg
https://i.postimg.cc/3NtkFHcs/IMG-0099.jpg
https://i.postimg.cc/xTq8Vh7d/IMG-0098.jpg
https://i.postimg.cc/d09wyjXX/IMG-0096.jpg