u/BackgroundGloomy3240

After 12 years, wife and I are reviewing our wills/revocable trust. I want to set up an irrevocable trust for minor grandchildren to be funded by TOD. New lawyer wants to do this within the revocable trust (which becomes irrevocable at death) and I prefer to keep the two separate since there will be different trustees. I don't understand lawyer's reasoning and they cat fully explain it.

Is there any reason not to have a separate irrevocable doctumten drawn up? We're in NH and I'm 87 so tie is important.