if you have multiple transmitters you probably need to identify the specific transmitter - I would use a structure which carries a transmitter ID plus the data. e.g.
struct Data {
int NodeID; // ID of transmitting node
int seq; // sequence number
int x;
float y;
char z[10];
byte crc;
};
how often do the transmitters transmit data?
what happens if two transmitters transmit at the same instant and corrupt each other ? will missing the odd data packet matter?