My take:
The Zales card is definately being included in calculation of % util, as it is the 10.2% being shown as the overall % util of the combined CL of $16,650.
That is a good overall % util. However, FICO scores both overall % util and the % util on individ revolving, and that one card is near 50%.
It is having some adverse impact, but is only one of five. FICO has never disclosed the relative weighting of overalll vs individ card utils in its scoring, so it is speculative as to the effect of that one card.
Ideally, each card should also be less than 10%, so improvement in util scoring would come about by paying that card down.
It represents future opportunity for quick score improvement, but unless she needs to app for new credit soon, it's kinda academic, as FICO only scores the currently reported utils.
The most significant factor, in my opinion, is low length of credit. Being added as an AU will provide improved length of credit, and thus possible score improvement, but AUs dont come without their own baggage.
Addition of the credit history of another in one's CR is helpful if used to app for credit that has a relatively low principal or revolv CL, as many of those creditors rely primarily on FICO score in their determinations. A great building tool. However, if apping for higher amts of credit, the creditor will most likely do a more thorough manual review. Seeing the credit history of another as a part of her risk score, they may wish to evaluate her score without that artificial score impact. They simply cannot do that, as they have no way of producing a score without that history.So it might discount the value of her score in their determination.
She has multiple revolving, and a mix of revolv and install. I dont see a screaming need for new accounts from a FICO perspective. And addted new accounts will, by definitiion, lower her AAoA even further, and also most likely have inquiries associated with their app process. I dont see need for new TLs as part of her rebuilding.
I see maturing of her accounts as the major factor, which only comes about with age.
Personally, I would be hesitant to add the account history of another to her score.
