Snacks. Especially healthy snacks. I'm at Atlas, but we fly to LEJ as well. I know if you were jumpseating to Leipzig with me, I'd make sure you and your stroller make it aboard if you bring snacks. Fresh fruit plates. Those giant buckets of cut watermellon. A big sack of apples. Tubs of those grilled chicken-breast nuggets from chik-fil-a. Those plastic veggie plates. All of that stuff would get your stroller to Leipzig.
In all honesty I'd still get your stroller aboard without snacks too. Also I don't fly to Leipzig anymore now that I'm on the 767. Still, if you bring snacks any crew would probably get your stroller to Leipzig.