can i force Bill Pay to send a paper check so i can put a memo?

I want to send an extra amount to my mortgage company (Wells Fargo). I need to put a memo line for them to apply it to the principle. When I enter the address, even if I do it manually under "pay a regular person", It still seems to match it with the official Wells Fargo Home Mortgage payee which is electronic, and thus no memo option appears when i try to make a payment.

(I can't pay them via an online account with them b/c the mortgage owner is deceased so they closed the online acct.)

i created an account with Fidelity just for this purpose b/c i heard they did have a memo line for Bill Pay. Is there any workaround?