hi there, How can I fill the void so that it remains the same as the rest
Have you tried using the Cap command?
delete those surface(s), see that there are no duplicating surfaces and that the remaining surfaces are joined, then use cap as Martin suggested, if the perimeters are planar. if they are not planar you might have to use different means, for further help just post that portion of your file.
Can’t tell because all the picture’s isn’t there, but could you just copy the next one over for the bad one?—-Mark