The father of missing child Haleigh Cummings' married his 17-year-old-girlfriend, who was the last one known to have seen the child alive, the girl's grandmother told Nancy Grace producers.

Ronald Cummings proposes to Misty Croslin Sunday at a local Chili's restaurant.

On Sunday Ronald Cummings asked his teenage girlfriend, Misty Croslin, for her hand in marriage at a local Chili's restaurant. While he was with several family members, Cummings got down on one knee, asked Croslin to marry him and gave her Haleigh's grandmother's diamond ring.

Because Croslin is only 17 years old, her mother filled out the paperwork so the two could be married.

On Thursday, the pair tied the knot, after the three-day waiting period required by Florida law.

Croslin, who was beaming earlier in the week after the engagement, told CNN affiliate WJXT-TV that while she knows there will be critics of the marriage and the timing, "everything is still about Haleigh."

Croslin said she wanted to be together as a family, just as Haleigh would have wanted.

"Everybody is probably going to take this marriage thing the wrong way," Croslin told WJXT. "This is what Haleigh wanted. She has always talked about it, and even if she's not with us, she is still with us."

Croslin told police she tucked Haleigh and her 4-year-old brother into bed about 8 p.m. February 9 in their Satsuma, Florida, home. She said she went to sleep herself about 10 p.m. but woke at 3 a.m. to find Haleigh missing and a back door propped open by bricks.

Police are still actively searching for the girl, with a new search happening this week, and investigators Wednesday took the back door that was found propped open.

In the middle of the search for the girl, the newlyweds will fly to New York Thursday night for their honeymoon and an exclusive appearance on the Today show.

Haleigh's grandmother, Teresa Neves, also acknowledged the timing might seem "unusual."

"Well, it is unusual for some onlookers, but those people didn't live with my two grandchildren," she told Nancy Grace. "My grandchildren, both Haleigh and Junior, have very often said that they would love for their daddy to marry Misty and that they wanted Misty to be their mommy. And so I feel like they are just trying to fulfill a wish for Haleigh so that when she comes home she will have that extra happiness to come home to."

Before the wedding, Neves told CNN affiliate WKMG-TV the wedding would be difficult without Haleigh.

"It's an event that Haleigh really should be at, but when she comes home, we'll have a great big wedding so she can be the flower girl and see it all again," Neves said.

All About Missing Children • Ronald Cummings