We will be arrive on 4/11/2020 (Sat) in CDG airport Paris leaving 4/14 (Tues) going to London then go back to Paris on 4/16 (Thurs) for our flight on 4/17 (Fri) in CDG airport Paris.
This is for 2 adults, 1- 14 year old. 1-6 year old.
Please see this page for ideas on which pass to choose:
How to Choose a Paris Metro Pass.
Don't hesitate to post another question if it's still unclear which pass would be best for you.