....Alternatively, you could ask yourself how film makers manage when they don't have auto focus available......
Many of the best film/video footage was, and still is, shot with fully manual lenses. Many pro cameramen will ONLY work with focus completely at their constant control. You have 'fd' lenses so what focal lengths do you have to play with?
All FD lenses have depth of field scales, and providing you examine your infinity focus to start with, the depth of field scales can be believed. If you choose shorter rather than longer focal length lens then you will have more depth of field to use. Pick f8 as a starter point with camera set to 'A'...ie, aperture priority,...now set to the hyperfocal distance for f8 by mo0vingn focla point on the lens to the right hand 'f8' position on D of F scale..........
......Now adjust the 'iso' for enough light to use f8,...in rooms you might have to use 1600 iso to allow f8...........Now just start shooting some footage, and then review it........concentrate on NOT going closer than your D of F scale tells you and you will be happily surprised!
Sit your youngster at the table (preferably in good window light from the side) with something she likes to play with or handle,.....place camera on some books at the other side of table,..check focus/framing and run camera,......talk to the child and get her 'going'...make sure theres lots of laughter.....Kids enjoy the 'game' of filming.....Good Luck!