I wanted to have a joint account with my family which would be 4 members and I trust all of them for our credit score to be linked. I was surprised to see that I cannot do that with monzo.
I had this for a house share with Lloyd’s back in 2008. Very annoying as we all needed to visit a branch to close it, never did and now we are forever linked on my credit record 
Sadly not in my experience. Not that I tried particularly hard, mind. My friends and I are still in touch 11 years later and (to the best of my knowledge) are pretty financial sensible. The only reason we never managed to close the account (despite being empty and untouched for ten years) was because we all had to go to a branch to do it together at the same time. One of us moved to Germany.