It strikes me that there is some issue between your nephew and his parents, mainly his father (your brother). This being the case, I would advise taking a step back from the tartan issue and let them sort it out between themselves. Nothing is to be gained by other family members, outside the immediate family getting involved. It will only exacerbate the situation and family wounds can last for years.

As to family records, photocopies should be available to all family members.

Regards

Chas