Molly has two parents and three brothers, which totals 2+3=<<2+3=5>>5 parents and siblings.
Since each brother is married with 2 children, then each brother has a family containing 1+2=<<1+2=3>>3 people.
Thus, the families of the three brothers contain an additional 3*3=<<3*3=9>>9 relatives.
In total, Molly has 5+9=<<5+9=14>>14 relatives.
At $5 per package, Molly will spend 14*$5=$<<14*5=70>>70 to mail the packages.
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