Delaying creating the sibling card – creating and suspending the sibling card (to be unsuspended later) – delaying introduction of the New sibling card using subdecks – you can see how those are all similar ideas. Yes, whichever appeals most to you and your workflow is the one you should go with.
I think you can. By default, all of the siblings should have the same New-queue number when they are created. If you’re studying them from the same parent deck, they will all use the same New card gather order. As long as that order is non-Random (so Deck, Ascending, or Descending), each subdeck will progress in the same order.
Sorry, I definitely don’t understand what you’re trying to describe! But I’m going to ask you to take a look at how parent and subdeck limits interact first – The Anki v3 scheduler - Anki FAQs .
I can tell you is that if you’re delaying decks B, C, and D – you wouldn’t face the situation where all of these cards would be in contention at the same time to be the next New card introduced. Card 1 for verbs 1-6 would have been introduced weeks ago in deck A, and you will just have started the tap on deck B, with decks C and D still having 0 limits. So in your example, you’d have some deck A card 1s, from verbs 50-55, and then deck B card 3s from verbs 1-6.
I didn’t factor into my suggestion that some of the cards wouldn’t exist – I don’t remember you mentioning that. (That would be a big consideration in any automated plan too – if the earlier card doesn’t exist, what would trigger the later card.) If that’s the situation, then things would need to be configured differently to make sure the later decks didn’t catch up with the earlier decks.
My suggestions aren’t the only ones, and they aren’t even necessarily the best ones for everyone, so have a look at the other approaches being discussed in this other thread – Bury siblings untill the older sibling is mature? - #8 by jambamboleo . I haven’t looked into those ideas, but it seemed so close to your question, I didn’t want you to miss it!