What site are you working on? This is the support forum for Galaxy Digital. We created the software that the organization you're wanting to volunteer with uses to coordinate their volunteerism. If you send me the URL, I can put you in touch with your site manager who can let you know how they would like you to sign up. The easiest way to indicate that you are coming with more than one person is to create a team.
Happy to help!
Shelly Tibbs is the Adult & Juvenile Alternative Service Program Coordinator - firstname.lastname@example.org
She would be a great person to reach out to talk about your and your kids volunteering. This article - https://galaxydigital.freshdesk.com/support/solutions/articles/36000041100-responding-to-a-need-as-a-team covers how to respond to an opportunity/need as a team.
Have a great day!