It can't. /overhead and /sweep are dedicated buttons that can't be in a combo, at least that's what it says in the wiki (the "Passing Link" mechanic).
Aside from , you can combo inputs as long as you don't repeat them twice in the same combo.
It's a system like in Under Night but does anyone know how many normals each character has, since the game has dedicated buttons for a DP, overhead, etc?
(Also no love for Europe...)