Fortunately Grandma is familiar with the general concept of cooking for those with food allergies/sensitivites. Both she and I have our lists of things that we can't have. I imagine she will find the cross-contamination issue easier to deal with than I will. I am checking this thread every so often as I clean wheat containing items out of the kitchen.
I may, however, need to have dh read information about cross-contamination. Thanks for that reminder. If he does not want to be careful I can always threaten to leave very, very hyper child in his care until it wears off.