Your state may be different, but in Illinois courts and lawyers typically use an incremental approach if possible. It rarely comes up on Illinois because all health insurance premiums are deductible from income for child support. If you know the price for employee only, employee + spouse, employee + child, employee + family, and other permutations, you can determine how much of the premium is for the additional individuals covered.
Now, if you have employee + family, the additional amount beyond employee, the incremental amount, is for the family. If you have more than one person in that category, a logical method would then be to divide the cost by the number of people covered, i.e. if you have three children and use your figures, divide 192-54.35 by three to determine the cost per child.
If you are unsure consult an attorney in your jurisdiction.
From $192, deduct the amount paid for adults. So if two adults deduct your 54.35 ( 55 for our example), and that leaves $137 and there are three kids and your spouse, the spouses share is 1/4 of the $137 or 34.25, so deduct that, leaving $102.75 per month for the children divided by 4.3 weeks in a month. Hope my math is right.