a suggestion for the 6 scenarios would be you must purchase at least 12 ships, but no more than say, 15. this guarantees at least 3 of the 6 will have multiple ships(if 3 were put in 3 missions), with as many as 5 or even 6 with multiple ships(combos of 2 or 3 per mission).
Another idea for you to maybe think about Jakle is one that I remember from a single ship perspective, but could be done with a team of say 3 ships. I would have to look up details on it for full info, but best I can recall, the ship( or in this case team) must fly a series of I think it was 4 missions with no resupply available. The 4 missions had specific ship combos to face the single ship(or in this case team). Each mission in itself was an easy victory, but with no resupply, the damages to the fleet keep adding up. I suggest this one to you as it can pertain to the thought of the deepstriking we do on D2. Later this week I should get some time to dig up more info on this if you are interested in hearing it.