No, it is not possible. First of all, MPNP do not allow multiple sponsorship to distant relatives and friends. I believe, a brother-in-law is a distant relative. This particular sponsor should sponsor his wife first. Then his brother-in-law and then his friend in separate time frames.
Although the wife is a spousal visa and the application is directly applied through the Federal government, as long as a sponsor is actively sponsoring someone, even if already under CIC process, a sponsor cannot endorse non-close relatives at this point. This is because a sponsor is responsible to the applicant's successful migration in Canada. One cannot take full responsibility of too much applicants whom the sponsor is not even closely related. This is why only close relatives are allowed for multiple sponsorship.
...hth
