My sister got sentence to 18 months in FPC Bryan Texas is there a way they can reduce her sentence and what does she need to do?

RDAP is the only way to reduce a federal sentence. If she has not filed her paperwork beforehand to prepare for the qualifications of this program it is doubtful she can get in. The reduction for RDAP inmates is 12 months; 9 months for sentences of 24 months or less.  Federal inmates have to do 85% of their sentence which is 15.3 months in your sister's case.