topping off carboy with opened juice?

Last Friday I hydrated a packet of cotes de blanc in apple juice and pitched to 3 gallons of store bought applejuice. I added one can apple juice concentrate, one pound dark brown sugar,and enough table sugar to bring the gravity to 1.090. I took a sample yesterday and it was down to 1.020. It tasted good but was still fermenting and bubbly and tasted strong of co2. The alcohol was a little hot but was fine and should mellow. It's in a 6.5 gallon bucket so I want to rack to my glass 3 gallon Carboy for less headspace.
If the cider level is low because of drinking the samples can I top off with opened apple juice That's been in the fridge? It's been open for about two weeks I think and I don't trust it because of bacteria spores or anything, maybe even my brother drinking some straight from the bottle, I don't want to risk it.Do you think it would be fine because of refrigeration?

What is your one real question here?

My mantra is if you question the sterility then don't do it. Just buy some simply apple to top it off. I have actually had my best cider ever from using that brand of store bought juice.

Yea the one question was if I should top off with opened applejuice that has been sitting for a while. I don't think I'm gonna risk it I'm just gonna get some new applejuice.

I know it doesn't seem like a important question, but i was wondering,the gravity is now 1.002 and around 12%alc, do you think spores would survive? Let's say mold spores got Into the refrigerated juice. Could these spores wake up and kill my cider or is 12% alc enough to protect from bacteria in the juice I'm topping off with?
I haven't read any forums about this, it would be great if the professionals would comment about this.

johnnybrew91 said:

I know it doesn't seem like a important question, but i was wondering,the gravity is now 1.002 and around 12%alc, do you think spores would survive? Let's say mold spores got Into the refrigerated juice. Could these spores wake up and kill my cider or is 12% alc enough to protect from bacteria in the juice I'm topping off with?
I haven't read any forums about this, it would be great if the professionals would comment about this.

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There is more than just mold floating about to ruin your cider. Acetobacter will turn your entire batch into cider vinegar, just as an example. Still likely tasty, but probably not what you are looking for.

If you're that worried, spend the $3 on some more juice and drink what you currently have as-is.