splitimage i'm so glad you are going! it will be inspirational and aide you to continue in sobriety.
if friends ask how you are doing, if it would be me, i'd say i was struggling to remain sober but keep coming back. my sponsor once told me i had "false pride". i said what????!!! she explained to me, my need to let others think i was ok when i wasn't. another saying she had, what others say about me was none of my business. i said what??!! she stated do you know your truth? does God or higher power know your truth? if you answer yes to both it doesn't matter what others say cause it's not the truth. so why care?

your family friend has no right to tell you that you must have God in your life to stay sober. she cannot define your higher power because only you can choose your higher power. you can make anything your higher power if it/they know more about successfully staying sober than you. that's why in the big book they even have that chapter re "to the atheist".

if you see your family member i'd acknowledge her and move on. she'll want to engage with you but it's ok if you choose not to. AA teaches us we don't have an obligation to like anyone. the only exception is if they need help staying sober. then carrying the message is suggested. you've already received the message and you have a sponsor. so her comments are not appropriate. you can thank her for her enthusiasm if you wish but you have a sponsor whose suggestions you follow. then repeat that over and over to her if she tries to push your buttons. she'll get the message.

enjoy your convention, benefit from it. try not to worry. that will negate the reason you are truly there.
looking forward to hearing about your attending!