The trend of using more than one type of wood to age or finish liquor has been going strong for years now, and many people have asked how they can do something similar with Beyond Barrels products.
The first idea that pops into peoples heads is to use two different staves inside of one bottle. This isn't recommended since it throws an important ratio way out of whack:
https://www.bbaging.com/blogs/news/112755716-bigger-is-better-barrels
It addition, it gives very poor control over the strength of one wood to the other.
Ideally, for every different type or toast level of wood that you want to use, you should age each one in its own bottle. That gives you control over the ratio of each individual wood vs the original liquor. In addition, after they are done, you can test out different ratios between the woods to determine the best tasting ratio.
Example: equal parts French oak #3 and American white #3 aged liquor might taste best... or 2 parts French #3 aged liquor to 1 part American white #3 aged liquor might taste even better. Its very easy to experiment like this to find the best tasting ratio if you use a shots worth or so of each and play with the ratios. If you threw all of the staves in the same bottle, among other problems, you will have a MUCH harder time experimenting with different ratios. You will be stuck trying to further age that bottle with one of the staves, completely guessing that it might taste better.
Aging with different woods in their own bottles and then blending is by far the best method because it gives you much more control over the strength of each wood relative to the original liquor, and it makes determining the ideal ratio of the woods to each other orders of magnitude easier and more precise than trying to do 2 woods in one bottle.