I was finally able to split my deposit from the suggestion of another user. Here is what I did:
I added a $50 savings bond, after which it asked me what I wanted to do with the rest of the refund. I choose ‘Deposit’ and it took me to the next screen which now had a ‘split between multiple accounts’ option at the top. I added my second bank account and was then able to go back and delete the $50 savings bond.