If you want another snake than you will need to get another enclosure, BP should not be house together.

There is absolutely no benefit in housing multiple snakes together however it can create problems such as stress, going of feed, spreading of diseases and/or parasites, premature breeding, you are also at risk for injuries, and even cannibalism.

Also any new animal MUST be quarantined for at least 60 days (Different enclosure, different room)

Proper substrate should be used for BP and sand is not one of them. You can use aspen, cypress mulch, newspaper, repti-bark etc.