Party wall between 3 houses will collapse soon

Trying to work out the best way to approach this so any advice or experience in a similar situation is greatly appropriated.

My house is a semi d with a large rear garden, there is 3 houses at the rear of my house that share a party wall with me, wall is 7ft high standard block.

House number 3 is the last house to share the wall and they have built a shed directly onto this wall, the roof is leaning on the top of the wall, the wall has been braced with 3x 6ft length strips of steel bolted to the wall from my side ( all done before i had moved into the house)

Now this wall is most likely over 30 years old and where he has put the shed has the wall leaning towards my house but the steel braces have the wall steady enough.

House 2 that share the next part of the wall with me which is next to this shed, the wall has cracked in the mortar so much so that i could look into next doors garden through these cracks, all theses cracks to my untrained eye seem to just part from the wall with the shed due to the lean on that wall.

House 1 and the last house to share the party wall with me has a clothes line attached to the wall, big steel structure with dual lines and winches, today i noticed that if i pushed against house 1s wall with medium pressure then the whole wall from house 1 and 2s wobbles (about 7 metres of wall) and i reckon if i pushed hard enough it would fall. The wall with the shed wont wobble as it is secure with the steel braces.

Any advice on how to tackle this, i think the wall will have to be rebuilt but getting 3 neighbors to agree on this is daunting.