Wine blending question (basic)

[Whatsgoodmiley]

I have 1 gallon of some wine that I have been brewing for my wedding. It is made from store-bought 100% white grape peach juice, FAJC, D47 yeast, a some yeast nutrient, and a touch of pectic enzyme. It has been going steadily for around two weeks now (cannot check how long, it is recorded on my phone which is currently dead and I am antsy to get started... airlock has been bubbling constantly). The goal is to make good a sparkling wine.

I want to add 4 gallons to this one gallon batch to make 5 gallons, enough for everyone to toast and then some. My only issue is deciding on how to go about it.

Should I aerate the 4 gallons of juice/FAJC and just siphon the 1 gallon batch into it (my fear is aerating the alcohol in the 1 gallon batch, I know that is bad), or should I just ferment the 4 gallons and the 1 gallon separately, then blend them after they completely ferment?

 

[Barley-and-Hops]

It is usually always recommended that blending occurs after the wine is finished aging with a careful bench trial. I understand how you would want to blend it early given that most containers are 1, 3 or 5gal. If you planning on doing nothing different with the new batch I would keep your 1 gal with head spaced topped up as you ferment the other 4 in a 5 gal container, then blend them on the first racking of the 4 gal. Definitely try your wine now and decide if you really want 5 gal of the same thing.