I have used stock/stock combination spread orders to take long/short pairs positions where I am seeking a specific spread difference in dollars. This order could be used for your set up except that it would be at a limit of $15 for buying both stocks rather than a specific limit price of $5 and $10 for each equity. If it's essential that you have both at the respective limit price of $5 and $10 and assuming you're at the computer rather than at a day job, set a limit price alert at $15. If it fires, check the respective prices. If one is above its limit, reset price alert and wash, rinse, repeat.
My suggestion is to call your broker and ask if they offer a conditional order that achieves exactly what you want. It would be more time efficient than the spread combo.