If I'm understanding your question correctly, given those...

If I'm understanding your question correctly, given those assumptions and assuming the price doesn't move from 15c per share after the SPP, there is no situation where you'd be better off not taking the full entitlement and just holding the initial shares instead. I.e. you'd always sell 6667 shares at 15c to fund the 10,000 shares at 10c.

I think in terms of technicalities, the way these rights work is that the share registry takes a snapshot of the amount of shares you hold at a certain date (pre-specified) to determine how many shares you are entitled to buy, meaning that you can sell your shares to fund the rights purchase and not impact the amount of shares you can purchase from the rights issue once the snapshot is taken. You generally have a week or two to send the registry money so you have time to sell shares on market to fund the entitlement buy too. Hope this helps.