If [P @ Q] means [P is wife of Q], [P+Q] means [P is father of Q] and [P - Q] means [P is sister of Q] then in [G+ H - R @ D], how is G related to D ?

"G is father in law of D"
G+H means G is father of H
H is either son or daughter of G
H-R means H is sister of R
R@D means R is wife of D
so H and R are sisters
and daughters of G
so husband of R i.e. D is son in law of G
or G is father in law of D