Is there any restiction to found a new enterprise?

How many sub-enterprise can I found under one parent company?

Can I found two enterprise and cooperate each other? Like company A build the terminal and then rent it to company B?

You may open as many subsidiary enterprises as you want. And as long as it´s inside one holding, you can cooperate between these enterprises.

Wolpertinger is correct, the number of subsidiaries is unlimited and their interaction is not restricted as long as they belong to one holding company.

I just want to add a little warning:

Very often subsidiaries are founded in other countries than that of your holding company. This scenario will lead to the situation that your subsidiary will not have any passenger traffic rights in its country and therefore is simply spoken completely useless (it you're not in the cargo business). So always make sure that your subsidiaries are founded in the same country as your holding company!

On a related note, can a subsidiary have a subsidiary? I recently noticed the following situation (the names have been changed to protect the innocent): airline "AAC" is a subsidiary of airline "AAB." However, airline "AAB" is a subsidiary of "AAA Group." Ownership of each subsidiary by its respective "holding" is 100%. How is a situation like this possible?

Yes, this is possible. In fact my "Sparrow Group" is like an airline but acts as a holding company and Sparrow Air is one subsidiary alongside Sparrow Connection. Sparrow Air itself maintains four subsidiaries (Sparrow Asia Airways, Sparrow Commuter, Sparrow Express, and Sparrow Regional Airlines). 

So you can imagine that my office in Jakarta is always busy  ;) and the scenery on the apron a nice mix of different aircraft-types :wub:  including the A319/320/321, Dash 8, Fokker 50, EMB120, Let 410, MD-80/-87, MD-90, Boeing 717/727/737/757, DC-8, Tupolev 154M, Jakovlev Jak42D, ATR42/72, CRJ200/900, ERJ-145, Fokker 100 and BAe146. Imagine the smell of kerosine and the noise generated by all the different engines :) .

Regards

Yes, this is possible. In fact my "Sparrow Group" is like an airline but acts as a holding company and Sparrow Air is one subsidiary alongside Sparrow Connection. Sparrow Air itself maintains four subsidiaries (Sparrow Asia Airways, Sparrow Commuter, Sparrow Express, and Sparrow Regional Airlines). 

So you can imagine that my office in Jakarta is always busy  ;) and the scenery on the apron a nice mix of different aircraft-types :wub:  including the A319/320/321, Dash 8, Fokker 50, EMB120, Let 410, MD-80/-87, MD-90, Boeing 717/727/737/757, DC-8, Tupolev 154M, Jakovlev Jak42D, ATR42/72, CRJ200/900, ERJ-145, Fokker 100 and BAe146. Imagine the smell of kerosine and the noise generated by all the different engines :) .

Regards

Interesting. Thanks for clearing that up!