My roommate is steamrolling me into letting a person I've never met and her 9 month old stay for 28 days in a room I share a wall with (VA)

Need advice on what to do about this. I live in a townhouse in VA with 3 others. The problem roommate is 29F, we'll call her G. In the span of 12 hours, G asked if this person and her 9 month old could live in a spare room since it was an 'emergency.' I promptly said no since that just wasn't happening in my mind. She then finally asks if we can talk about it, I say I can the next day (still only ~6 hours since she asked), she then says 'ok well I am gong to greenlight her since she has to give notice....' I say no, we call and I am now going to talk to her hopefully today to see if she's a normal human. Honestly, I don't think she can say anything that would make me say yes.

Not sure what to do, I feel kinda powerless, lease agreement of course is on my side after reading it. Part of me wants to go to leasing office since I don't like G at all anyways and try to get her booted. Any advice on what to do is greatly appreciated and feel free to ask questions if I left stuff out.

Edit: Thanks for all the advice on this. It's an obvious hell no on this happening, my plan is going to be to talk to the leasing office and make them aware of the situation. Fingers crossed and will update on aftermath.

Final (Hopefully) Update: Had a brutal conversation with roommates and G, tried asking questions about this person's situation and what happens after the 28 days, lots of ifs and maybes so nothing changed my mind. G freaked and started imposing rules on random things in the house, medium level freakout but nothing major, I told her it's too much of a risk and liability, roommate said while I was 'over concerned' G tends to overcommit to things when people ask her of things. Person's mom is 'going through a divorce' and has 'financially abused' person before so living at her moms is 'not happening.' There is someone living on persons couch at her current apartment so she is trying to move out of there. When I asked G when conversations about her moving into ours started she said in the last 5 days. There had been some leeway to guests before (mom from India stayed to visit for a month) but none with kids and none with as loose of plans as this person. While to G, I look (and feel) like the bad guy, I interpret this as pulling off the bandaid and curving any potential BS this could accrue down the line. Also seems like this person just doesn't want to live at moms 🤷‍♂️ . Welp, I'll be walking on eggshells in my place now.