Apologies, I had assumed it was all merit.
But I still wouldn’t hesitate to share details of other packages. They may or may not be able to adjust the need-based award but you’re not slimy for asking. This is common practice among even the most selective schools, with the rationale being that fit not cost should be the primary consideration for students (yes, there are other reasons but that’s a prominent one).
This is very different than something like a negotiation at a car dealership. You’re just making them aware that other schools have calculated your ability to pay differently, trying to understand the difference, and asking if they have leeway to recalculate your ability to pay. That’s all very legitimate and if handled politely will not offend anyone.