Hannah This is a problem with every family that I know, one member is prepping and the others are not. It is hard since if there is a SHTF we will have to feed them too! They will come to your house. So the plan is to make sure to have more food and have them do a job at your house, like be the look out. So buy more ammo and guns for them too.
I just had my roof repaired and asked the roofers what will they do if there is an SHTF. They said they only have money for the week of food so they do not know what they will do.
I think they will hit all the houses that they think have food so be ready.