me'ispe lujvo

s1 is a sister's spouse of m2 under law/custom/tradition/system/convention sp3.

Omit x4=s2=m1. Cf. speni, bunspe, tubyspe, speme'i.

In notes:

be'aspe
x1 is a daughter-in-law/son-in-law (a spouse of a child of) of x2 according to law/custom x3.
bunspe
s1 is a brother's spouse of m2 under law/custom/tradition/system/convention sp3.
spebu'a
x1 is a brother-in-law (brother of a spouse) of x2 according to custom/law x3.
speme'i
x1 is a sister-in-law (sister of a spouse) of x2 according to custom/law x3.
spetunba
x1 is a sibling-in-law (sibling of a spouse) of x2 according to custom/law x3.
tubyspe
s1 is a brother/sister-in-law (brother's/sister's spouse) of m2 under law/custom/tradition/system/convention sp3.