The first name, last name and address must be identical. If your middle name is Steve and first account has First name Steve last name and second account has First name S. last name then you cannot transfer and you would need a medallion stamp. Same goes for address. Feel free to try (as I didn't have tried all the variants) and I will update the post with other experiences

I encountered a lot of problems on my way to transfer from one account to another. At one moment I considered it impossible as the medallion stamp is very expensive / impossible to obtain outside US. So when I tried to transferred the shares I forgot to leave one / some in the old account. I will try this in the future

I know about changing the name or address. But it is not clear what the brokers can use to unDRS. If the key is the account number, then having a new account created with GiveAShare could avoid this situation. Maybe there are other ways to avoid this but I feel that it's better solution for the moment, as there are so many things not clear

After I transferred the shares from the old account into the new account, my old account (number) has disappeared. All my shares were in the new account. Then I was interested what would happen when I would DRS again (from the same old initial broker): would the shares land in the old or new account ? After I DRSed the shares, I found them into the new account (the one created by GiveAShare). I don't know for sure, but I feel that this could mean that the broker could have a direct connection to my new account. I'm still exploring as there are a lot of things to try 😁