The question and your problem is based on a lack of logic and understanding. The gender of a noun in Latin is imminent for that noun. For sure, on a verb/predicate in a sentence can be applied several genders: Servus clamat - the slave cries. AND: Servus et serva clamant. The slave and female slave cry. If you have more, then you use the plural of the nouns: Servi et servae clamant. I do not really see where your problem is. However, I hope it is clearer now.

Thank you! That's what I was looking for. :)

Any combination of people in Latin with at least one male will default to masculine plural. Any group of things of varying genders may default to neuter plural. However, Latin often will violate this kind of logic and simply make an adjective agree with the closest noun even if it applies to both linked nouns---for absolute clarity you can separately place the adjective in agreement next to each.