We went to Ischgl with a similarly diverse group the year before last. We booked everything in one order through GetSki. For each item, we specified our skill level and preferred ski type. The company prepared everything individually for each person, and there were no problems. You can check out the options here: https://getski.com/ . We chose soft, basic models for beginners - myself included - while the more experienced skiers opted for stiff, expert-level skis for dynamic skiing. At the rental shop, they handed everything over in a matter of minutes without any confusion. By the way, we are heading to La Plagne this season. Have you been there?