Standing ovations are not uncommon in Minnesota, the land of 10,000 obligatory hand claps, but I’m pretty sure “Sisters of Peace” is the first time I’ve seen a standing O before a show began.

The applause that greeted the introduction of the four actual McDonald sisters at opening night of History Theatre’s “Sisters,” the Doris Baizley bioplay about them, was an early indication that response to the comedy/drama would be as much about affection for the elderly activists as it would be for the play itself. Sometimes sounding more like a debate than a dramatization and too often telling rather than showing, “Sisters of Peace” is not a great play. But the sisters are a force of nature.

Rita, Kate, Jane and Brigid McDonald are played, respectively, by Wendy Lehr, Katherine Ferrand, Sue Scott and Peggy O’Connell. You know how you (hopefully) have that one person you always invite to dinner parties because they’re fun and make everyone feel comfortable while you’re in the kitchen finishing up the béarnaise? All four of these actors are so charming and genial that I suspect they fill that dinner-guest function for their pals. Almost as much as the McDonalds, who still campaign for justice on the Lake Street Bridge every Wednesday, they are Twin Cities treasures and it’s a kick to see them getting a bang out of each other (the production color-codes the sisters, with Rita always in green, Kate in yellow, Jane in blue and Brigid in red, as if we need ROYGBIV to distinguish between these indelible talents).

“Sisters of Peace” is more a series of linked sketches, representing the sisters’ greatest hits as they campaign against war and greed — and for the rights of Native Americans, LGBTQI people and women. Although the back-and-forth structure is wobbly, Baizley has a knack for crafting conversational zingers such as Brigid’s “There’s so much marching since Trump!” and the oft-arrested Rita’s “Yes, officer, I was being sarcastic. Is there a law against that now?”

In the first act, we don’t learn much about the sisters; the most vivid person, in fact, may be their father (a lovely performance by Terry Hempleman), who can’t understand why his daughters keep turning their backs on his world. But second-act flashbacks hint at why each McDonald felt called to become a nun (with the aid of Sonya Berlovitz’s costumes and a whole lotta Velcro, quick-changing Annick Dall plays all four of them as young women, even while representing several other characters).

The play spans almost eight decades and, as with biopics that attempt to pack entire lives into a few hours, there’s a sense that none of these events gets its due. But History Theatre deserves a lot of credit, and many full houses, for tackling this story. Because there’s no question that the McDonalds deserve greater fame and that these four actors are the perfect people to help make that happen.