More Than One Wife in Bed
Q: If a husband has more than one wife, can he sleep with them together in one bed?
A: If by sleep you mean normal sleep then this is permissible just as it is permissible for two strange women to sleep on one bed. However if by sleep you mean sexual intercourse then this is not permissible for two reasons.
1) It is not permissible for the one wife to look at that which is between navel and knee of the other wife.
2) It is not permissible for the one wife to view the other wife in sexual activity with their husband.