how to send email from a separate address

[shred_head]

i use gmail,
i have multiple emails forwarding to the one main account that i actually check

it is this MASTER gmail email account that i check on my phone,
but if someone was to send me an email to one of my child email accounts, i can only reply back to them with this MASTER gmail account address,


is there any way around this?
or is there a gmail app that i can use on the phone in place of outlook to acheive these features?