No, the sister sites are not included. AmazingEmbroideryDesigns has its own membership, the others don't have one.
For your membership you can download all existing designs and the new ones for the coming 6 months.

It is worth the membership. So many other digitizers charge the same or more for 1 set. I have not regreted the money at all. I know I can trust Miss Veronika's designs to stitch out perfectly.

What are the Other links? So I can go check them out. I love to Support the Digitizers. that try to keep this Hobby Cheapor For All to enjoy..
Thanks so much.
Lwatts

Here you go Linda, Aorable app has a free one a day that is voted on, a Wednesday extra, and deals- when new ones are put up. A minimum amount when you buy, but not much. Very nice apps, I've gotten some of the towel toppers, also.
Amazing Embroidery Designs has designs and alphabets. A free, voted on one per day, and a membership.
Cute Alphabets has...alphabets. A free voted on one per day, and sales at times-like now.
Happy looking!
Jo