Cute people getting mired in a cute situation? Good. Cute situation getting mired in unimaginative slapstick? Not so much. This is yet another one of those movies about characters who have clearly never watched a romantic comedy. If they had, they would know that: trying to break up a loved one’s wedding two days before it is scheduled is not a great idea (“My Best Friend’s Wedding,” “Made of Honor,” etc.). You only embarrass yourself by showing embarrassing footage of the bride at the rehearsal dinner (“27 Dresses”). Wandering off by yourself on a visit to the prospective in-laws often results in getting wet and ruining property (“Father of the Bride”). Taking a wedding-related movie down to a PG instead of a PG-13 is usually a sign that the studio does not have much confidence in it (“Bride Wars”) because the script is weak. The characters in this movie are the only ones on earth who haven’t been there, seen that.

It is a cute situation. Marni (Kristen with an “e” Bell) is a smooth, capable, professional woman who is proud of triumphing over her teenage years as an ugly duckling, constantly abused by the mean girls led by head cheerleader J.J. (Odette Yustman). Her comfort during those years was her golden boy brother Will. Now Will is getting married to none other than Joanna, formerly known as J.J. The calm, professional Marni instantly reverts to a cowering mess, and then things really get complicated. It turns out Joanna’s only family is her aunt Mona (Sigourney Weaver), who is none other than the former BFF-turned WFF of Gail (Jamie Lee Curtis), mother of the groom — and of course of Marni as well. Add to the mix a wedding planner (Kristin with an “i” Chenoweth), the bride’s ex-beau, a wise-cracking granny (Betty White, of course), a dance-off, a fluffy dog, and a dad who eats his meals blindfolded (okay, that one I didn’t see coming), and you have pieces that never quite work.  

Just to see the glass as half-full for a moment, I’ll point out that this movie does not have a big but highly touchy client who gets caught up in the chaos or a child to spout out-of-the-mouths-of-babes wisdom.  There are no funny clergy.  There are a couple of genuinely welcome surprise cameos.  Weaver and Curtis do their best to elevate the material and sometimes succeed.  

On the glass half-empty side, there is an icky dentures joke.  Serious injuries are dismissed as blithely as are serious infractions of trust and good judgment.  It is under-written, running out of steam — and ideas — long before it is over.  Ultimately, there’s too much com and not enough rom.