My dog didn't dig enough holes for it to smell. Not to mention...I kept refilling the holes and covering it back up.
I don't have siblings...but that doesn't mean we don't have sibling rivalries here sometimes.
Ramsey is the oldest at 2.5 years...then Reese...1.5 and Reggie who is 6 months.
Their play is really rambuctious...complete with growls, nips, barks, and bites. It's how they play and sounds much rougher than it is. Sometimes Ramsey is not interested in Reggie's puppyness and she lets him know this. I don't see the behavior as aggressive...it's the only method she has. It's much how their mother's corrected their behavior.
I have witnessed real fights between Ramsey and Reese...I am quite aware of the difference. I break it up...but honestly...minutes later they have both forgotten the entire ordeal. No one is mad at anyone.
Females...sometimes have a problem getting along. They are usually more dominant and independent than the males. It may improve if they are both spaded. I have friends who have females...and each of them has told me...their females fight.
So there...I wrote a book without any real answer for you.
Try asking in the general forum...or pm yorkierose. She breeds and has dealt with the female problem before.