Uk visa application

hello, I have some queries regarding plab 2 visa.
if you guys can help us out would be really grateful.

In short,we are currently holding a one time entry PR visa for Canada which expires mid March 2023. it means we have to get in Canada by this time to get our visa updated and eventually be a PR later.

we have already booked for Plab2 on 1st week of March and we are planning to go to UK first, take the exam and then fly to Canada from there. problem is, our 4 year old son will be accompanying us. we have already managed Nursery for him at our convenience in Salford, UK.

my wife have a savings account which holds I think enough to sponsor me and my son. can we apply all together, my wife being the main applicant and we( me and my son) being dependent/sponsored ? of course with explanation about the source of money.
or it be better we applying separately with my son on his mother’s application?

what will be easier for us if you guys can give an idea since we are into a lot already, don’t want to make things complicated.