Rescued pregnant Chihuahua

Hi all!

So, I have a bit of a situation. I recently adopted a 2 yo female 3lb Chihuahua from a couple who needed to rehome her. I've had her for a week. Well, they had no idea she was actually pregnant. She wasn't really showing.

I was planning on starting to train her to get used to being in different situations, meeting the family and all that. That's on hold now. She's learning to trust me, and she's been ok with my son, I imagine because we're the two who are around her most. She's still a bit wary of my husband (he works a lot so he's only around a few hours a day), but doesn't react to him, just gets nervous.

However, she has been reacting to my mom (my parents live in the front house while we live in the back house). She gives her the whale eye and stare down, and even growled a bit and barked the other day. She will still take treats from her but it's clear she isn't comfortable. Now, partly it's my mom's fault, she tends to put human emotions on animals so she'll smile and wave at her which I know is adding to it, so I'm trying to get her to understand not to do that. I have her give my dog a few treats and that's it. The fault on me is my trying to soothe her, but I learned that that just encourages the behavior.

I don't want my dog to become reactive, but I also don't want to stress her out because of the pregnancy. I know being pregnant can make her a bit more guarded as well.

I'm just looking for advice on what to do. I've never dealt with this before. Should I have my mom come over and spend a bit of time but just ignore my dog? Give her some treats and then just leave her alone? Any help is appreciated.