The sandek is the highest honor given at a bris. Oftentimes today this honor is bestowed upon a grandfather. As such, it may be uncomfortable choosing one grandfather over the other. The sandek has both the responsibility of holding baby on a pillow while sitting on a chair that marks the throne of Elijah(see more on this special chair here, and the role of putting wine or grape juice to baby's lips while Hazzan Glantz does his work.
Therefore, Howard can easily use two sandeks and each will play an important role. The honor of sandek need not be limited to males or grandparents. Read more about the history of this role and the possible origins of the term 'sandek' at wikipedia.
Kvatterin and Kvatter:
An Ashkenazic custom, the female usher (kvatterin) takes baby from his mother and hands him to the male usher (kvatter) who ultimately places him on the pillow on the lap of the sandek. There can be more than just hese two ushers. Sometimes people equate this role to the term 'godparent'. While there is no conflict if the individiuals chosen to be kvatterin and kvatter are also to be announced as godparents, it is certainly not a requirement. Historically, this honor was usually given to a couple trying to have children of their own.
Another Ashkenazic custom is to light candles as part of the bris ceremony. They can be any candles and candlesticks you wish and there is no blessing that need be said.
Hazzan Glantz has several readings you can choose or adapt and give to whomever you would like to include. Of course if someone prefers a poem or writes their own, this can add a beautiful personal touch.
Choosing a family tallit and wrapping baby during the passing can be expressed as a way of welcoming the generations that went before as well as connecting to the future.
For clarification of any of these ideas, or other practices you might like to incorporate in your celebration, please be in touch.