How can you merge Multiple Internet Connections on single PC at same time?

If it is Windows xp or above version. Goto Control Panel > Network Connections. If all your internet connections are listed there, select two or more (including your LAN) and select Bridge connections from the Right Click options menu. This will result an another network bridge which allows other PCs on the LAN to connect to the internet.

If you would like to know more about Multiple Internet Connections and its advantages like Load Balancing, Redundancy please visit this link to gain knowledge http://www.wanredundancy.org/resources/technology/networks-and-technology/multi-wan-broadband.html

A better option would be to use this

http://www.softpedia.com/progViewOpinions/MultiConnect-98000,.html

I am using it and its good