Legal Question in Family Law in California

I assume that you mean that your husband is paying child support for children from a previous relationship/ marriage. The fact that he has new children is a factor in calculating guideline support. It would qualify for what is known as a hardship deduction.

New children to either parent always affect child support. Without knowing who has the child it is impossible to say how. Since you say "if we" it sounds like you and the husband who is paying support would have the child. That would affect things for sure, since it would void your separation and possibly all support. If you mean "we" you and a new partner, than that is a whole other situation.