There are two scripts you can use, one checks if T3M4 is in the current active party, and the other checks if T3M4 is available to be chosen in the party selection screen, you didn't state which so i posted both.
Below is the script that checks if T3M4 is available to be chosen at the party screen.
Code:
// This returns whether a NPC is in the list of available party members
int StartingConditional() {
return IsAvailableCreature(NPC_T3M4);
}
There are already preset scripts for both K1 and K2 which checks for party members in the current active party, you didn't say which game it is for so I'll put both:
K1: "k_con_t3m3pm" (without the quotes and it's NOT a typo)
K2: "c_con_t3m4pm" (without the quotes)
Hope this helps.