AU does not help much in building credit, especially if mortgage is your ultimate goal. During mortgage, everything will be manually reviewed, and any AU account is going to be ignored at that point.
I see you already have a personal loan from CU, so that is a start. Pay off that loan and get a credit card from the same CU. Building credit does not just happen in a blink of a eye. A good credit means at least one year of good on-time and continuous payment from loans and credit card.
I agree with trumpet-205. Credit will be a big factor in a home mortage. And if you don't have any...god only knows how they will work around that.
It's interesting that the mortgage lender told the OP to become an AU on a card themselves. If the lender told the OP to do this then why not do it?
Also, if and when the AU account shows up on the OP's credit reports that could help him/her get a CC of his/her own, no? If the mortgage lender questions that then the OP could explain the reason behind it.
Just my 2 cents.
We don't live at the same address but they assure us it will show up so I don't know. The lender suggested this to try and jump my score. I had two car loans. One in 2005 and one in 2008, both were paid off as agreed but that's all I have. He said he trusts I will pay and I have to income to pay just wants to get my score up. But, after the loan and AU accounts, my score has done nothing so i don't know what else to do.
It is up to you to build your credit, not with the help of AU.