Indie ADR: Critical Fix vs. Luxury Performance Tweak?

Hey everyone, location scout here, dipping my toes deeper into post-production budgeting discussions for an upcoming indie feature. We’re outlining the post-sound budget, and the guide I read suggested a tiered approach for ADR: critical fixes vs. performance enhancements. This makes perfect sense on paper for cost-saving. Our director, however, views every minute performance nuance as absolutely essential. We shot on an AMIRA with MKH 416s for dialogue, so the core sound is decent, but some lines just need that extra push. When the budget is tight, and you've got a director who wants to fine-tune even a perfectly audible line for a more 'authentic' emotional delivery, how do you realistically differentiate between a 'critical' fix (e.g., a completely unusable line due to a car horn) and a 'luxury' performance tweak (e.g., slightly altering inflection on an otherwise clear line)? How do you negotiate that without alienating the director or blowing the budget?