I think the stones are perfect, I like to think lucy is ''snuggled up'' with her grandad, but also has her own space for her own things too... the best of both .
my grandad died when Ethan was born ,and was cremated but had asked my mum to hang on to his ashes until my gran dies so they can be scattered together but when Ethan passed away too , my gran gave me a small gold box containing a tea spoon amount of my grandad ashes which went in the coffin with ethan so I know he isn't alone but my grandad and gran can still be reunited when the time comes .
this is what my grandad would have wanted too if he knew Ethan was only lent to us , not given..
I'm sure you dad is Honoured you wanted Lucy with him if she couldn't be with you but probably agrees with you that it is lovely she has her on space too ...

for lucy kisfor her grandad too