I just got word my MIL has THE FLU! She will be coming over Thanksgiving morning and we are going to be cooking dinner together. I already give my 2 1/2 yr. old DD echinacea plus a multi-vitamin, but I was wondering if it is safe to slip some liquid echinacea into my DS's bottle to boost his immune system a little. He is just now getting over a cold DH brought home last week and when he gets sick he usually gets it the worst because he's asthmatic

I'm just being a paranoid mama and I hate when my babies are exposed (even though we love grandma DEARLY

)...this is kind of one of those unavoidable things being that it's Thanksgiving.
I read the back of the bottle and the youngest it said is age 1-2...up to 24 lbs. My DS is 8 1/2 months old and is 21 lbs. Should I hold off? Thanks