You sell your property and then buy someone else's property, that is wasting time and wasting money. It only makes the government, lawyers and property agents very rich with all the stamp duties, legal fees and commissions.
What I suggest is that proud owner sells his property to ay123, and ay123 sells his property to proud owner.
I think what you are looking for is that caveat record stating that you bought this property House 123, AY Road, for $1.5 million in 1999 and then sold it for $2.8 million in 2010.
Then you will feel very happy, "realising" $1.3 million of gain. Then you use that $2.8 million to buy #12-03, Proud Mansion, just to create another caveat record so that hopefully in another ten years, you can again create another caveat record at a higher price.
I tell you there is no need to go to all these trouble.
You can just look at your neighbours' transactions, and know how much your properties have appreciated.
I subscribed to Realink (by SISV) because URA doesn't provide house or unit number so I won't know how far the house is down the road; or which floor if it's a condo. However, nowadays there is this Streetsine.com which provides house and unit numbers as well.
Whenever the transacted price goes up, I go to my EXCEL spreadsheet to update my property portfolio, and the figure goes up. Also can feel equally happy. No need to sell in order to feel happy.
That's why I get very angry with those idiots who fire-sold their condos. It caused my spreadsheet figure to go down in early 2009. Now fortunately it's gone back up again and surpassed the previous peak.