How do you say this in English (US)? заодно [context below]

See a translation

@Qonshab0 @alliebitz Thank you very much for your help!
Could you tell me, please, whether you also use this expression or not:
“while you are about it (Go and see what’s the matter, and while you’re about it you can fetch me my sweater)”? [it’s from a dictionary]
Is it common?

@alliebitz I got it. Thank you very much again!

@edwardws Thank you! That was very helpful.
I also checked this word on Academic, actually:) But, as you said, there are quite a lot of options there, and I was confused which one to choose in each particular case, and which of them are normally used. So, yeah, thanks. Your answer is very on point, and it helped me a lot.

@edwardws BZW, a little tip for you. In 99% of the cases, we use the word печенье as an uncountable collective noun. So if somebody asks you принести печенье, неси целую пачку:D, because they want some cookieS. And we’re so used to this word being a collective noun almost always, that when we’re talking about one cookie we tend to use diminutives, wich are countable nouns (принеси мне одну печенюшку/печеньку), even though одно печенье is 100% correct, because technically печенье can be used as a countable noun as well: одно печенье, два печенья, пять печений и т.д.

@edwardws What you see here https://www.gastronom.ru/binfiles/images/201809... is печеньЕ (not печенья).

And there https://lenta.servicecdn.ru/globalassets/recept... are разные виды печеньЯ (not печений).

We use singular uncountable noun for ‘cookies’:)

@edwardws hahah no problem!