Yes, combo orders can be partially filled while maintaining the exact ratio between legs.
Example:
If you place an order for 10 butterflies with this structure:
Buy – 1 - BTC-16MAY25-100000-C
Sell – 2 - BTC-16MAY25-105000-C
Buy – 1 - BTC-16MAY25-110000-C
Your order might execute:
7 butterflies (7-14-7)
4 butterflies (4-8-4)
Or any other quantity that maintains the 1:2:1 ratio, but never with an uneven ratio like 10-15-10, preserving your strategy's intended structure.