My former employer (I resigned in 2021 due to moving far away, on good terms) contacted me in October to ask for an up to date CV. They were negotiating some deal and they wanted to include the CVs of the team who had been involved in building the product. I thought it was a bit weird but I needed to update it anyway so I used it as a push to get it done, and I sent it.
I was pregnant and already on maternity leave during this exchange, and told them
do.
Now they've contacted me again saying hello, hope you and the baby are well, and to ask if I'd be happy to do a phone call with some new members of staff to share my insights about the product. They're trying to do a new deal similar to one I pulled off when working there.
I feel it's a bit too much to ask?
The woman asking isn't junior but she's in her twenties and doesn't have kids, and I feel like saying, "when you're looking after a baby, I find that there is one slot in your day, maximum, where you can find time to do a task, like call your bank, do an exercise video or something. That's a very precious chunk of time I have per day, and if feels too much to use that to give professional advice for free."
I bet they're asking partly because they think I'm on maternity leave so I must have loads of time 
I'm due to move back to this town soon and I will need these contacts to find a new job, so I don't want to burn bridges. It's also a quite informal company (start up, 10 employees) so it wouldn't be appropriate to send something really huffy.
What would you do?
Thanks