I'm a newbie but I think I can answer your question because I'm facing a similar issue.
In short: NO
Your EO is the essence of the aroma. Adding something with no aroma to that is not going to make more aroma. You can do only two things: (1) use more EO, or (2) make a smaller batch.
Yesterday I did my first batch, 1 fl. oz. tangerine EO to 3 lbs of oil, and I can barely detect the scent in the completed soap.
I've got some lemongrass here and might even use it today, 1 fl. oz., and to my sense of smell it's about the same strength as the tangerine I used yesterday. I know for sure that the 1 oz. lemongrass won't put any usable scent in today's batch, so I'm going to cut the batch size down because I don't want to buy more EO at the price I paid at the nutrition store. In fact I have to order EOs today on the Internet so I can get a better, non-ripoff price.
So either get more EO or make a smaller batch. Your 0.5 won't do it.
EDIT:
I should have mentioned, I'm using NOW brand. YMMV
Just to be thorough, you have three problems: not enough scent (IMO), lye, heat. That's presuming you're using CP. You might lower the lye by picking low SAP oils, you might be able to add the EO at a cooler stage, but I doubt you would be able to make more than a minuscule change and you might chunk your batter before it goes in the mold. If you can't get more EO and won't reduce your batch size, then you can divide your batch and scent only part of it.