I would like to send my son age 11 to his aunt’s (mother’s sister) bungalow for 4 weeks. husband is only home for weekends thursday night till monday morning. she has three daughters, age 3, age 6, age 8 or 9′ is there a issur yiuchd.
The prohibition of Yichud applies to an eleven year old with his aunt. Proper shemira is therefore necessary. When the 6 or 8 year old is at home with the mother, this provides shemira and there is no yichud. At night, an additional shomer is necessary, and both the 6 and 8 year old need to be present. They provide shemira even when sleeping. The 3 year old is not a halachic shomer. When the husband is around, your son may be in the house with his aunt as long as her husband is in the vicinity.