Hypothetical Party 3/6 situation

[ZootMurph]

My circle of poker buddies has an ongoing argument about this hypothetical situation. I'm posting here hoping to get more insight or fresh thoughts/input on this.

For this situation, assume you have joined a Party 3/6 table within the last orbit and have no reads. The table is 10 handed. There are 3 limpers to you. You have 76s.

1) What do you do, and why, in MP3?
2) What do you do, and why, in CO?
3) What do you do, and why, on the Button?

I won't go into the details of the argument, in hopes of not skewing anyone's thought process here. I welcome and appreciate any responses with reasoning included. So thanks in advance.