Mixing After Fermentation but Before Bottling

So I have searched many websites and forums but could not find an answer, if this has been discussed before I apologize.

I am pretty new to brewing (3 batches in) but want to make a chocolate-strawberry extract beer for February. After reading through some posts it seems that chocolate is very overpowering which makes the choco-strawberry combination difficult.

My thoughts were to brew two separate batches: 1.5 gal choco, 3.5 strawberry completely separately and combine them right before bottling. In my mind it makes sense but due to the different density, FG, amount of sugar, etc I am hesitant. Anyone have any advice or experience doing something like this?

Thanks in advance.

How I would do it is to brew like normal but using less chocolate so it doesn't overpower.

From my experience strawberry as an addition loses itself in all but the lightest of beers very easily so use a lot more strawberry than you would think necessary. I recently did a 6bbl batch of a strawberry blonde and used 75# of strawberry in it, the taste was very subtle even though I thought it would be too much. If I were making a darker beer or using chocolate I would probably come close to doubling that amount.

I know the scale is different than you are considering but it is just to give you an idea of how easily it can get lost in a more complex beer.