Hi Tonya,
I checked Fort Bend county marriages and State Death Record index.

1. Marriage Records
There were several Mallorys in the index. Only one for a George.
George & Mill Sanders married 3-10-1895
No James listed.

Was Harriett the wife of Robert Mallory? They were in Fort Bend in 1880, as you probably know. There was no marriage record listing for a Robert Mallory.

2. TX Death Index
There were only 6 listings for Mallory in Fort Bend county ( TX Death Index). None of them George, Jim or Harriett.

A Robert Mallory was listed in the death index for Dallas county, TX (1922). Could this be your Robert? Where was he in 1920?
Note: I found no record of a Robert in the marriages (yet).

Have you found ANY of these Mallorys in the Death records in another county? The key is knowing the approximate age and location of YOUR Mallorys in the year THOSE Mallorys are listed in the Death Index.

Tell me more, if possible. What 'specific' blocks do you have with these family members? Where have you found them? When were they in Fort Bend county? Where were they in 1870?, 1880?, 1900?, 1910? (etc.)