Managing My Disney Experience for multiple reservations

I’m managing a group of 12 people planning a trip for next September. There are three households part of this trip. Is there a way for me to manage and link all the reservations and tickets so we can have FastPasses that are the same since we plan to tour together? If we make a FastPass reservation for 12, can we also make three separate dinner reservations, since it is likely difficult to make one reservation for 12 people.

What is the easiest way to deal with a group this size?

Yes you can do all those things. I’ve never done it so not speaking from experience.
I think my biggest suggestion would be to have ONE designated person on MDE to manage all the FPP/ADRs. Also, don’t expect that all 12 will want to tour together for the whole trip. Following to see what others have done.

I’ve been planning for a group of 10, also 3 households. I use my MDE as the main account and made all FPPs and most ADRs from there. The tricky part is managing ADRs with only one account. I had to make one for my sister, which I also manage, to be able to make multiple reservations within the same time slot, as we won’t always be eating together. Any reservations for the 10 of us were made on my account and extra ones, where we break up into two groups of 5 were made through my sisters.