Can an entire Will/Trust be frozen if someone has child support issues?

It only directly affects him: distributions to, or payments made to or on behalf of, other beneficiaries are not liable for his child support issues. Your money and property is not subject to his debt.
That said, there could be issues for the other two of you to resolve, even though your share of the assets is not, as stated, ultimately subject to his debts.
For example, if the Will/Trust has physical property in it that all of you have interests in, that property could be affected. Example: the three of  you inherit a house. Say that you want to sell the house. A lien for unpaid child support could be placed on the home, and the home could not be sold without satisfying or paying off the lien. Even though it's just his share of or interest in the home that is subject to a lien, by the nature of liens and real estate, it impacts the rest of you and must be resolved pre-sale or paid at closing.
Or take a bank account, from which money is being paid. If there is a single account (instead of separate accounts for all three of you), it would be possible to initially freeze the account to make sure that the money to be used for his child support obligations is not drained, hidden, etc. The other two of you could go to court and get a court order that you can withdraw your portions, etc., and that only his share is frozen (or levied upon), but you'd need to go to court and deal with the situation if there was an attempt to lock up the account.
So longer term, you will get your shares. But short term, there could be complexities or situations to resolve due to his debt.