Mother Died Intestate, Sister Uncooperative

Mother went in for surgery and unexpectedly died of sepsis a few days later. This was 10 months ago. She had given sister a power of attorney to pay bills out of her account while she was in the hospital.

Sister took all the money out of mothers account and transferred it into her own. We are 5 kids and only found out because months later one of the siblings discovered it.

She’s spent money on home renovations, vehicle expenses, etc.

My father lives in the family home, he’s been profiting from mothers money as well. He says they will spend the money as needed and whatever is left can be split between the 5 siblings after he passes.

One of my brothers and I spoke to a lawyer and notary, the say we need a liquidator and the title of the house needs to include all 5 siblings since mothers passing. We’ve sent letters, lawyer has sent letters requesting banks statements, we’ve only received partial copies, lines blacked out, etc.

Bottom line is they’re refusing to cooperate, 2 other siblings are taking her side and we are being accused of being greedy. Father threatened to remove us from his will if we insist on fighting for mother’s inheritance. Brother and I are ok with that.

Is suing sister the only avenue?