Two sets of siblings, one being the upbeat sibling (Phineas and Mabel) and the other one being the more laid-back and articulated one who has a thing for older, teenage girls (Ferb and Dipper), from iconic Disney shows set during summer, with both pairs of siblings trying to make the most out of it. However, during this they get involved in extremely wacky, supernatural, or particularly odd situations. Throughout their summer time they are accompanied by one of their grumpy relatives, who despite this seem to love and care dearly for them and vice versa (Candance and Grunkle Stan), their untradicional pet animal (Perry and Waddles), their friend who is very clearly a different ethnicity of them (Baljeet and Soos), a bully character who eventually became friends with them (Buford and Pacifica), the girl who either has a thing for the protagonist or the protagonist has a thing for (Isabella and Wendy, with Isabella crushing on Phineas and Dipper crushing on Wendy, and also Vanessa if including Ferb), as well as some other friends along the way. One of these previously mentioned characters (Perry and Stan) is hiding a secret they don't want the protagonists to know about (Perry actually being a spy working OWCA and Stan working to bring his brother back via a portal under the shack), which eventually gets revealed later on during their series, which temporarily caused a rip in their relationship, although this eventually was resolved. They have once stopped an interdimensional invasion perpetuated by a being ironically coming from some sort of 2nd dimension (Bill Cipher and 2nd Dimension Doofenshmirtz).

Kinda sad that this MU doesn't really work that well (mostly due to the fact Phineas and Ferb's arsenal is much more varied and crazier, even if the Pine Twins still have their own set of gadgets) cuz otherwise this would be a really great idea