Mel B Wants Permanent Sole Custody from Estranged Husband Stephen Belafonte

Mel B has made a major change to her divorce petition ... she does not want to share joint custody with Stephen Belafonte for 2 reasons ... a domestic violence conviction, and a gun.

TMZ broke the story ... when Mel B filed for divorce last month she said she wanted joint legal and physical custody. Sources connected with Mel tell TMZ at the time she had no idea Stephen had a conviction for domestic violence involving another baby mama. She also didn't know the conviction prohibited him to possess a gun.

As we reported, Mel knew he had a gun and was not happy about it, especially since she alleges he repeatedly committed domestic violence against her. But we're told after recently finding out the gun was illegal to possess, she decided to change her custody strategy.

We're told Mel, who just got a temporary restraining order which prohibits Belafonte from having any contact with her 3 children, will go back to court and make the restraining order permanent.

Our sources also say in the divorce case, she does not want Stephen to have any contact with 2 of her kids, one of whom is 10-year-old Angel, whose dad is Eddie Murphy, and 18-year-old Phoenix -- a child from another marriage.

We're told Mel might ultimately be ok with giving Belafonte monitored visits with their child, 5-year-old Madison, but not now.

Belafonte has asked for joint legal and physical custody of Madison.