A variety of things that can help in surviving any gig, even when standard equipment is lacking or outdated…
In your mixing workflow do you tend to use subgroups, VCAs, or both? How do you tend to organize them, and what advantages are afforded by that workflow?
Consider how the mix sounds without that missing instrument and start making changes to close the gap.
Our panel of audio veterans on getting a better handle on “those things with strings.”