Joint cash management accounts

My partner and I share a property (both on title). I manage the property (using Stessa), but the mortgage is only in her name. Our mortgage company doesn’t allow setting up auto pay from an account in any name other than the mortgage holder. I initially created a Stessa Cash management account in my name. It would have been awesome if I could have added my partner as a joint owner of that account so that I could pay the mortgage from this account.

Instead I ended up having to open a separate cash management account under her name (separate entity). This was a relatively painless workaround as this account is linked to our property and it was easy for me to transfer funds between the two, but joint accounts would still be great!