would ask all other ip's in the same subnet what their MAC address is
No - you can only see MAC addresses for the local subnet. You'll only see the mac address of the router (via TCP/IP) for other subnets.
and change the route table?
!!!! even if you know the MAC address of the remote machine, that's got nothing to do with the routing table
Your description of what you are trying to achieve is totally confusing.
needs to track slave machines on the local network
OK, let's start with that.
There is no 'slave' in the TCP/IP nor OSI network model. Only servers and clients. The server knows who the client is because it has a fixed address (and usually an IP name). Even where that is not the case, the client can discover servers by probing open ports.
An alternative approach is the peer-to-peer model - where there are multiple servers. There may be a hierarchy of servers, in which case each server will maintain a directory of (some of?) the other nodes and their position in the hierarchy. Where there are insufficient nodes within a particular level of the hierarchy, then the node detecting this should request an election from the nodes in the level below.
A brute force approach is for a prospective client to send out a broadcast request for a server.
If you're talking about authenticating the end points - then that's a completely separate ball game (unless all the relevant nodes are within the same VPN).