The court will only inquire into this if some interested party--someone who stands to inherit (such as yourself)--challenges the appointment in court, by claiming (and providing some basis or evidence for the claim) that the proposed representative is unfit for the role. If no one challenges the appointment, the court does not take it on itself to look into this. If you are concerned, therefore, you need to challenge the appointment of your siblings (and potentially put yourself forward as a candidate); either speak to a probate attorney about having the lawyer bring the challenge for you, or else contact the probate court clerk's office and ask how you challenge someone's application for this role.