If you can't do it, just outsource.
If the people already offering this service on this forum are doing great, what's the need for others
I created a small mother/child service some years ago after figuring out the method on my own. I was just shouting out my mother account on the child account and it worked fantastic for me. I get interaction on my mother page all day long, just like the video said, because I shout out the mother multiple times a day. The page is always buzzing with followers, likes, and comments.
However, it did not always work for my customer's accounts. If their mother page was dead, with nothing to do/see/get, then the method did not work since there was nothing to interact with on the page. Only about 6 out of the 50 Instagram accounts I tested from customers converted well, but none of the customer's mother pages converted as well as my own mother page.
I run contests and all kinds of other things on my mother and child pages. When they play a game on the child page, the prize is on the mother page. Along with more games to play to make them stay on the mother page and follow it.
So, this business is a really good idea, but it is hard to scale if a good portion of your customers do not have a mother account that has some kind of reason to follow it. People will ask for a refund when they get no followers or interaction.