She will presumably have completed Court forms about her finances as part of the divorce process. I do not know what (if anything) is on these forms about notifying any changes that occur in the finances before the divorce is complete. If there is something imposing an obligation she needs to consider carefully the possible implications (legal ones) of not complying by withholding the information on the inheritance.
How long will it be before the decree absolute? How long will it take to wind up the estate and pay out to the beneficiaries? (If you are executor you could perhaps exercise some control over the speed of this process.) It could end up that the money is not available until after the absolute decree, but I don't know whether this would make any difference to what I have said above.
In any case, it seems to me that it would be best - if you can arrange it - for the money not to be paid until after the absolute stage.
I can't see that there is any legal bar on the money going into the childrens' accounts, but does she have the power to take it out again if she wishes? She also needs to consider the tax implications of this so far as interest on the accounts is concerned.