My dog who has sired 7 litters ,in the last two litters to different bitches there was a dog puppy in both litters with a mismarked white side of face
i have his daughter and was looking at a young dog with a view to using him with her in the future
Thing is although he is only slightly mismarked  slightly white just on the eyebrow would it be quite likely that a litter between these 2 would produce mismarked puppies

You obviously haven't stated breeds - but are these merles?   Or are either of them from a solid/merle breeding?

Let me see if I understood.
You wish to mate your bitch to a young dog with a very slight  mismark?
The straight answer isn't very precise, it may or may not mean puppies will be mismarked. As your bitch isn't she could possibly correct the fault in her puppies but she could also carry the problem recessively and the puppies could infact be worse than their sire with the problem doubled up.
The problem is you are not certain where the white faces  in the litters sired by her father have been inherited from.

No not merles

Your bitch is carrying her Father's genes to produce mismarks and so I wouldn't consider using a mismarked stud dog on her ........
Why would you consider doubling up on a fault?

hi there ,a basic rule of thumb is "what you put in will come out eventually". if white markings are a fault i'd be looking at only using dogs without mis-marks in an attempt to reduce this fault appearing,which may even skip a generation, otherwise when you breed a fantastic litter it may be the typiest who ends up with mis-marking.unless your gene pool is so small you have no choice,where possible i'd make it easier on yourself by narrowing the chances of white appearing rather than increasing it.in theory youre introducing the white gene and it may be near impossible to eradicate it from future litters, and the white patches may increase in size/shape/placement as there is a wide scope for the white pattern to express itself,from white blaze on head to white on paws to white bib or patches.hope this helps,roy.