What happens to your reservation is not inherently linked to the ticket. If you have ticketed the segments open-dated, have a paper ticket, and have made separate reservations then you are less likely to have problems. The only tricky bit is if you have a transit coupon you may be asked at check-in to prove where you have transited from; if you can't then there may at least be a tax liability, and if turning a transit into a stopover would be against the rules of the ticket then you are likely to have much bigger problems..