What Happens when a finches mate/pal dies

So ever since Angelina died Lacey has been extremely lonely and depressed and has been under weight and has had loss of her appetite and considering what social bird finches are I understand why she feels this way. So I have been trying to get her weight up using baby bird formula which is a good option for adult birds who are under weight. On top of now trying to make her gain weight I’ve been researching getting her a new friend that is of a different finch species as there are different finch species that can’t breed (have babies with) As well I think at this point she’d be better off with a Male finch and if i get the right species they can do whatever and not have babies. But as well you have to look at how aggressive other species of finches are cause some species are more aggressive/dominant than others. One common species that is mixed with zebra finches is society finches and they are of the same temperament as zebra finches. However there is literally nothing on the internet about if they can breed together or not so I decided to call Doogans a pet store in Barrie and the owner knows me very well and has been a saviour in some of my bird good & bad situations. Anyways I called her and told her everything and she said she was pretty sure they could not have babies together however she would call her finch supplier and double check and call me back Monday. The reason I’m so thorough with this is zebra finches gender can be determined by colour but with society finches they don’t have any distinguishing colour traits (same colour for both genders) To be able to tell the gender. So if I did request a society finch and asked for a certain gender they can tell other ways that don’t rely on plumage but there is still no guarantees. Anyways I’ll be keeping you updated on what happens and what I end up doing in case your wondering what a society finch looks like here are some pics down below.