[ReVo_]

pawn Code:

#define STRING_TO_FOUND     "hi"
    #define STRING_TO_ADD       "hello"
    
    new text[128] = "hi, whats up? im here for u";
    if(strfind(text, STRING_TO_FOUND, true) != -1) {
        new pos = strfind(text, STRING_TO_FOUND, true);
        new length = strlen(STRING_TO_FOUND);
        strdel(text, pos, length);
        strins(text, STRING_TO_ADD, pos, length);
    }
    print(text);

this little code's example maybe can help you.. i do this fast.. im not sure if it work