It's quite possible, but it would help if you could tell us how much your testers weigh. Let's say, to follow Patience's example, that they weigh 30 oz between the two of them. At 9%, this means they contain 0.09 x 30 oz = 2.7 oz of fragrance. The rest, 30 oz - 2.7 oz = 27.3 oz, is pure wax. If you add the two candles to the batch, you'll have 27.3 oz + 70 oz = 97.3 oz of wax in all. To get a 7% fo load, it takes 0.07 x 97.3 oz = 6.8 oz of fo. Since the testers already hold 2.7 oz of fo, you need to add 6.8 - 2.7 oz = 4.1 oz of fo. You can calculate the real quantity you need by replacing the 30 with the actual weight of your testers. Hope this helps!