This is the first time Brian Krause appears in the opening theme credits.
The Family Tree shows that Phoebe was born November 2nd, 1975 which fits with the line, "Mom's barely even pregnant with me" from 1.17 "That '70s Episode" when the original Charmed Ones travel to March 25th, 1975 to stop Nicholas.
While looking over the family tree, as they come across the 3 names that were most likely to be their own past lives from the '20s, the one in the middle has to be Piper's past life (P. Baxter) because she's the only one showing as married. Her husband's name on the family tree is Gordon Johnson. When Phoebe used the spell to see her past life, "Piper" was married to "Dan" - whose last name is Gordon.
The family tree shows that Melinda Warren is about halfway down, revealing that there are generations of ancestors that preceded her and were documented on the family tree.
Dan Gordon was Penny Grams Halliwell's father in his past Life.