The training for keep kids well behaved in Mass starts at home. I’ve seen families with children who are rarely disruptive during Mass and I’ve seen families where the children always are disruptive during Mass. The main difference between these two types of families is parenting.
Those parents who allow children to be disruptive in all situations, home, school, out shopping, during events are the ones who are going to say why won’t my kids behave at Mass. The answer is if parents do not make kids behave in any other situation, why would you expect them to behave at Mass.
The flip side is this. Children who are taught to be polite, have clear expectations from mom & dad, are aware family rules and the consequences for not following them will have a much better time at Mass. Of course all of this is based on the child’s age. You won’t have the exact same expectations for a two year old as you would for a child that is 8.
No child is expected to behave perfectly at Mass. The biggest issue is the amount of disruption.
To help with this do not allow the children to talk during Mass (outside of the Mass responses).
Do not let them chat with siblings or others. Of course if there is a bathroom break needed they can let you know.
Do not allow them to move around the pew. I mean changing seats constantly, walking back & forth in front of the pew or on the back of it. Have them follow the postures of the Mass as best they can.
Make sure they’re not hungry, thirsty, or tired before Mass. I know that is much easier said than done but try to choose a Mass time that works best for your kids if possible.
Talk to them before Mass about what you expect from them. Talk to them after Mass about how they did, keeping to the positive.
None of this works on the first try and will only work if you & your husband are on the same page. And remember you are working toward behavior from your children that is respectful in all situations not just Mass.