You need to stay calm!
if she thinks you’re upset or anxious (even if the cause of the anxiety is her kicking off) she will think there’s a reason to be too
if you react strongly you will i brain this behaviour and have a lot of follow on problems.
note the trigger points so that you can preempt the behaviour. Is it a certain distance, is it in a certain room?
you need to reassure her you feel safe so things like sitting down and continuing to talk normally will help reinforce there is no big deal here.
if she starts to seem anxious but hasn’t reacted yet sit down get her to come and sit beside you and just casually keep talking with her chilling beside you.
If she starts barking or exhibiting behaviour you want to stop ie jumping up, spinning in circles, yapping repeatedly, getting between you
make eye contact, hold you finger up sternly pointing at her and say NO firmly and forcefully.
then bring you finger down to your side and call her to come sit by you. Don’t make a big fuss when she does just reward her with a wee clap for coming and then carry on the conversation
the most important this is that your behaviour reassures her and de-escalates the situation
if you start to get anxious, fretful, frantic, agitated, shouty or start locking her away from people so she never sees them then you will reinforce that something bad is happening and have a full scale behavioural problem.
right not what you have is a trauma response and being firm and reassuring will soon me she’s not worried as long as the situation isn’t repeated.
probably best she isn’t around your family member again. If she hurts them to protect you it’s her life on the line so it’s your job to never put her in that position