Not to be confused with the Mother's Day in which Rebecca De Mornay killed a number of people, this one will, unsurprisingly, tell the intertwining stories of several mothers as the day approaches and they wait for their bunch of daffs. Or whatever.
Marshall aside, the film has slightly different DNA to its predecessors. Anya Kochoff-Romano (Monster In Law) and Lily Hollander replace Katherine Fugate as the writers, and while the previous two films came out of New Line, that's not a done deal this time. The "package" is "going out to buyers" shortly.
It will, however, mark a reunion for Marshall and Roberts: their fourth collaboration following Pretty Woman, Runaway Bride and Valentine's Day. Don't take the latter as evidence that Roberts will reprise her previous character though: Jessica Biel and Ashton Kutcher were both in Valentine's Day and New Year's Eve playing different roles each time. Maybe they'll show up in this one too.