my wifes dad, was a pretty big collector, his son died when he was 16, & my wife tried as best she could to fill her big brothers shoes... her older sister, & her husband had no interest & hated guns... I think he was pleased as punch, when my wife & I started dating... & I think he groomed me to take care of his collection after he was gone...
I took to the responsability as best I could... 1st thing I did, was give all his shooting buddys, cousins, & other family members the chance to buy at current market prices, any gun that held special memories to them... only 5-6 family members took me up on the offer, & we lost all 3 of the 30-30 lever action rifles, along with several other interesting guns, but I was comfortable all of them went to good homes... next I sold off the "junk", & any of the pieces that didn't seem to follow some sort of theme... next, I used that money to add to the collection, & help incorporate the guns I'd bought before he died into "the" collection...
Honestly, you never know what your heirs will attach themselves too... some of what means the most to me, are guns that meant the most to him... if you do not have a couple "jr." guns, I agree with adding them, in the format of your particular collection, to get them shooting & interested... those 1st guns might mean the most to them down the road, or it might be the rifle they borrow later in life, that they shoot their 1st deer, or the shotgun they got their 1st pheasant, or whatever with, & they ask to borrow every year after that ???