Activity for Kori

Is there a courteous way to indicate how many guests are invited on an invitation? For example, my aunt is dating a new guy who has several young children and they now live together. My aunt's children (my immediate cousins) are definitely invited...

I've been gathering package information for photographers in our area and I've noticed some offer a package that includes two photographers or an option to add an additional photographer for a small fee. Do I really need two?? Help.