Frank Jr. Jr. is the eldest of the couple's triplets: the other triplets are his younger sisters, Leslie Buffay and Chandler Buffay. Frank Jr. and Alice had trouble conceiving naturally, so they asked Frank's sister, Phoebe Buffay, as a wedding present, to be the surrogate of their child. He was born in the episode, "The One Hundredth", along with Leslie and Chandler.
A year later, in "The One With Joey's Porsche", Phoebe was asked to babysit Frank and his sisters. Near the end of the series, midway through season 10, Frank Jr. shows up again when the triplets are five years old and asks Phoebe to adopt one of them (similarly to "The One Hundredth", where Phoebe asks Rachel to ask Frank if she can keep one of them). Frank then realizes that he loves Frank Jr. Jr. and his sisters too much to let them go.
Phoebe Abbott is not Frank Jr. Jr.'s grandmother. To make her the grandmother of the Buffay triplets, Phoebe Buffay would have to be their biological mother. Frank Jr. Jr.'s father and Phoebe Buffay share one parent, and that is Frank Buffay Sr.
- By exact definition, Frank Buffay Jr. Jr. should really be known as Frank Buffay III. When this was noted by Chandler during Alice's discussion with Phoebe about the names she and Frank had chosen for two of the triplets, she implied that she had attempted to explain this to Frank, but to no avail, although Junior could be his middle name.
- Frank Buffay Jr. Jr. is 22–23 as of 2021.