[Mirkawolf]

I agree with Nanouk. Introducing now a third dog into your pack, male of female, might be a big problem. I do not know, why of all things you think about third dog, but o.k., some people have more dogs and they like it. However, according to my opinion, it is not at the moment, considering age of your dogs, the best idea.

I have several reasons to think so:

1) Your younger female is not mature yet. As a CSW, she probably was not in heat yet, and she will be fully mature in 2-3 years. Many many things might change between the two females in that time. The younger one will not always be a puppy. It is very probable, that the younger CSW will sooner or later challenge the older female for position in the pack. It is natural for these dogs and if you do not prevent it (by training and maintaining the alpha role in the pack, and the order in the pack yourself), there might occur fights in the pack of two girls later.
I´ve heard about this to happen too many times to think, it would be different. For the idea that "mother" and "daughter", real ones or not, will get along better, that is total utopia. Several cases from my friends families prooved, that "daughter", usually real one, took over the mother´s position as soon as she matured .
Therefore, introducing another female into this situation, would be highly risky. The relationship between the two females you have now, might change greatly once the CSW goes in heat and matures. Bringing another female would and could unbalance the relationship they have now. Two CSW females, if not trained, socialised and kept in their right hierarchy order, will sooner or later fight each other.

2) Bringing a male into a pack of two females, is also very bad idea. And that from several reasons. First, the two females might and probably would start to fight each other for the males attention, especially when they go in heat. The male will choose one he likes more, and he together with this female might even try to turn against the other female.
A male (non-castrated) will also suffer, when the females are in heat and he can´t cover them, yet he smells them and know they are there. He will (especially if it is CSW) howl, stop eating and will keep crying for good two or three weeks. Nothing to enjoy, really.
Plus, to prevent unwanted matings, you have to keep them separate in these periods, it is all more difficult to handle and gets on nerves for everyone.
So unless you plan to breed, or at least you plan to neuter the male, getting a male is not good idea at all.

3) A puppy CSW, if introduced into a pack of two dogs, is very likely to get attached to them and less to their master. It requires twice as much effort for socialising and training and education, to raise the dog to be fine in the head and at ease with people and things. You´d have to take the puppy on walks also alone, without the other dogs and devote it a lot of time. I am no beginner, but I think I´d not feel like getting a third CSW (puppy) to my two girls.

4) Last but not least, males are not so easy as females. They tend to be more dominant, more territorial, more stubborn and harder to manage. Especially males CSW are hard to deal with and they do fight other male dogs, if they get a chance. Do you really want that?