As the dictionary entry below lists, 同 in Cantonese means
for, on behalf of.
In Cantonese, you might say something like this (slightly aggressive tone): 你同我企喺到! ("You stand right there!")
1) Would 和, 跟, or 给 be the right Mandarin substitute in this case?
2) What's the right substitute for 你同我畀錢! ("You pay for me!")