Hi Scared Silly
That's a difficult situation and no wonder you feel torn, I'd be too , your daughter and son in law supporting your granddaughter moving in with you. Do they talk with you about your granddaughter's BPD and situation, do they understand her struggles and theirs as a family? I ask as you are concerned about your son in law's behaviour towards your granddaughter, you are trying to work through that it may not be environment for your GD to recover, I understand that, if it was, what needs to change apart from the yelling? I can understand you feel stuck and speaking out may cause friction. How and when we speak out can make a difference. Have you read the tools to the right
'Know Good vs Bad Triangulation'?
Since discharge is your granddaughter receiving treatment and support?
SS my 29DD was hospitalised a number of times and diagnosed in 2015 I know where you are and yes a calm, loving, supportive, validating environment was key to her recovery to where she is managing her BPD. I see you know that well and want that for your GD.
Small steps worked for me and my 29DD. I stood back and leant how.
We can help you move forwards. How's your lovely GD today? How are you?
WDx