I read the question as asking whether a stereocenter bearing a C-Mg bond will keep its configuration. The answer is yes, but not indefinitely. Unfunctionalized (alkane) Grignards of this type racemize/epimerize with a half life on the order of hours. Specific compounds will have more or less stability. By analogy to organolithium compounds, I would expect having Lewis basic atoms in the proximity to stabilize the configuration. I'm not sure if this is still an active field of research, but it certainly was for a long time. Try searching "configurational stability of Grignard reagents" or similar search terms.
There's an additional complication with these chiral Grignard reagents: they can't be prepared by the usual method of oxidative addition of Mg(0) to an alkyl halide. The mechanism of that reaction goes by a single electron transfer, through a radical intermediate, destroying any stereocenter. Chiral Grignards have to be synthesized using less direct methods.
Ref: Side Reactions in Organic Synthesis: A Guide to Successful Synthesis Design, pp. 200-202.