The sandek is the person who holds the baby when the mohel makes the bris. Generally this honor is given to a grandparent or very righteous person. In many cases when preparing the baby to perform the milah the mohel will help the sandek where is best to place his hands, hold the baby, knees, feet, etc. Generally the sandek has to hold the babies legs so they shouldn't move. The question was asked if the sandek for whatever reason is unable to do this, may someone else hold the babies feet and still have it considered to be that the "real" sandek is holding the baby? Does it make a difference if someone must assist in this matter.
(The question was raised and I have no reason to believe that it should be an "issue" but you never know...)