I had a long post typed up in this thread last night and one of the cats turned the computer off

It is completely normal to feel nervous and anxious when adding a new dog to the household, especially when you're worried about how your baby girl will handle it.

How old is Samantha? I was thinking she was around 2 yrs, but can't remember for sure. If you do end up adopting a female dog, I would try to be sure that there is a considerable age gap (about 2 years) and size difference between Samantha and the new dog. The more the dogs have in common (gender/size/age), the less clear their ranks in the pack will be and the more they will have to struggle to work it out. They would be the same gender already so f they have a good age and size difference, their positions on the hierarchy will be clearer to them and there will be less of a chance of them butting heads and fighting for the same rank. In general, the older larger dog will be higher ranking than the younger, smaller one. You always have a chance of getting a really dominant puppy though so you have to watch out for that. It is usually apparent pretty quickly.

I think an older puppy is a great idea. Sometimes a young pup will be submissive, but once it hits adolescence, they will start to challenge the other dogs for a better spot in the pack. If you get an older puppy, you will have a better chance of knowing the personality and it will be less likely to change.

I don't know how you feel about male dogs, but maybe Samantha will be more comfortable with a male.

Of course every dog is an individual so when you fall in love with a dog, I'd just be sure to spend some time (a few different visits) with the dog so you can get a good feel for the personality and judge how you think Samantha will react. When Samantha does meet the dog, it is best if done on neutral territory.

Crates are always helpful in the process of introducing a new dog to the home. The dog should learn how to be comfortable in his/her crate alone. Then you can give Samantha periodic breaks so she won't be bothered constantly by the new dog.

I wish I didn't lose my first post, I had a lot more written.

Anyway yes, I think you should try for an older puppy I don't know about Chloe. I know a herding dog like that would drive my dogs NUTS. But I'm not sure about Samantha. If she'd be fine with that, I'd go for the introduction.