affinal relative (see Lockhart); a relative through marriage (see Molina)
Lockhart tells us that Molina equates tehuanyolqui with pariente and "blood relative," in a compound form that includes cihua- (woman-), intending "affinal relative." But, under "teuayulqui," Molina gives "deudo o pariente." Lockhart says deudo is broad and vague in terms of familial ties. See his discussion about a distinction between blood relatives and people united by ties other than blood.
These terms deserve careful study if we are to come to understand better the Nahua understanding of concepts akin to "family." See also cemithualtin and cihuahuanyolcayotl.