I had a single 3 year old female, Gigi, when I bought another young female. The baby was intensely interested in Gigi and followed her non-stop. Gigi was perhaps afraid and eventually the baby began to bully her. At the end Gigi was unable to eat without the baby chasing her off. After 3 months that baby was returned to my friend, the breeder, and she went on to bond with a male and have a clutch of babies herself. So my experience was terrible and if I'd have the chance to do it again, I would choose a male partner and just intervene if eggs were produced. I think 2 males are often a better bet too.
But with that said, if these 2 girls have been together perhaps it will work out well. Linnies are often sweet and gentle and get along well with all other Linnies. My experience might have been an unfortunate exception. Now at 5 Gigi is fine and seems content as a single bird. We are retired and give her lots of attention.
Good luck and we need pictures!