` And Carrie Underwood just confirmed that she will be on the show this spring . ` How I Met Your Mother '' executives wanted to introduce mother ##hood . Rachel Griffiths , Stacy Lewis and Carrie Underwood all cast in 100th episode . Underwood tells writer that Bilson is too obvious a choice .
` ` How I Met Your Mother '' executives wanted to introduce mother ##hood . Rachel Griffiths , Stacy Lewis and Carrie Underwood all cast in 100th episode . Underwood tells writer that Bilson is too obvious a choice .