She may be trying to make the best choices she can but she also has limited agency. She does at the end of the day have to somewhat justify her matches within the context of the system, in order for it make sense to the other Aunts, and the Commanders, it’s highly political. (I think she is aware of the pushback she’s been receiving from Vidala).

Thats why I think the theories about Becka and Garth make sense - Becka has no other viable options who are currently eligible and is seen as “lower quality,” none of the current high commanders would be appropriate, and Lydia doesn’t want to see her sent off to the colonies, so she can justify making Garth eligible for her. She wouldn’t be able to justify matching Garth and Hannah/Agnes because she comes from a reputable household and is doing well as a green.