Punki, Not
Allowed! Sorry to rain on your parade,
(I'm just the messenger). 
Those are indeed,
Back-To-Back tickets in spite of your creative packaging. You are using portions of two roundtrip tickets to circumvent their "rules." Using United Airlines as an example:
United Airlines
Tickets: Back-To-Back -- Rule 100C
Use of coupons from two or more tickets issued at round trip fares for the purpose of circumventing applicable tariff rules (such as advance purchase / minimum stay requirement) is not permitted.
United agents and authorized travel agents are prohibited from issuing tickets, commonly referred to as "back to back ticketing", under such circumstances when there is obvious intent to abuse and/or misuse restricted round trip fares.
Agents found issuing such tickets may be liable for the difference between the fare paid and the fare for transportation used. United Airlines has the right to deny transportation to passengers found utilizing tickets in this manner unless the difference between the fare paid and the fare for the transportation used is collected.
Rule 100 C / 22nd revised page UA-7 / May 9, 1996
The following is from
1Travel.com's "Rules Of The Air, know all the rules before you take off!"
If United Airlines determines that you have purchased back-to-back tickets, they have the right to deny you boarding unless you pay additional money (the amount you saved).
If you purchase back-to-back tickets and are not stopped at the airport, United Airlines has another option. They can bill your travel agent. The business agreement between your travel agent and United Airlines requires your travel agent to abide by all United Airlines ticketing rules. Writing back-to-back tickets is a violation of United’s ticketing rules and subjects your travel agent to a debit for the fare difference - the amount you saved. This debit, of course, will be passed on to you.
Years ago I was advised by my travel professional that they would no longer issue back-to-back tickets to me. They informed me they could be liable (for the difference) and would naturally have to charge my account. Prior to that time I hadn't even realized that it was against any rules. I simply thought I was being a savvy and prudent consumer. Some of my high school teachers would have been proud of me! I still try to be, though,
every chance I get.
Here are some interesting links:
1.travel.com: Rules Of The Air
http://www.onetravel.com/rules/rules.cfm
Passenger Rights.Com
https://www.passengerrights.com/
Best Fares: Consumer Complaint Links To Make Your Voice Heard On Airline Issues http://www.bestfares.com/member/desk.../10012751L.asp
Travel Rights Galore
http://ww2.blp.net/blpnet/article.html?article_id=13236
[This message has been edited by MRLIMO (edited 10-11-1999).]