Is it possible to have a tricolour with full black markings and a tri with partial black markings from the same parents?

I imagine it is possible but I just want to check.  I've today met again a little loopy tricolour collie, met her once before as a pup.  Very sweet dog.  She also happens to be from the same farm as my Phoebe, and I suspect they are full sisters - not from the same litter, she is 3 years younger, but possibly the same parents.

This is Phoebe:
https://lh6.googleusercontent.com/-FG4JKj0Ei74/UMSpUU3IRlI/AAAAAAAAAQY/00f36UPLAFc/s912/CAM00043.jpg

And Holly looks just like this:
http://www.bordercollies.es/colores/tricolor5.jpg

Phoebe's coat is longer naturally, for her own sake I keep her trimmed so she looks more like Holly (bad experiences with grooming in the past so it's better for her if she's kept short).

I expect this is a very silly question but my coat genetics knowledge is dreadful :-P

they're both black tri... if one was 'white factored' then more/less white is perfectly possible

Do you mean Blanket tri as opposed to Broken tri (if we were talking hound colour descriptions), then yes as the only difference is the genes governing amount of white.

They are both Tricolours, but in Phoebe's case her white pattern is 'covering up' most of the areas where you would see the tan markings.

Quite probable - as Penny said, if one is white factored - and that's something you'd know if you could look at both parents' pedigrees/colouring.

With our Aussie litter, Loki was a black tri (from a black tri mum and red tri dad, which gave her the red factor) and the stud was a blue merle, also with the red factor.   So in her litter we had two black tris, two blue merles, one red merle and one red tri!   One of the black tris had very little red compared with the other.

the white is actually areas which 'should' be black - in tricolour collies the tan is only on the 'points' - on the face, feet/paws, around the tail etc... and can be variable amounts... the white factoring gives 'broken' coat where it 'should' (excess white isn't ideal) be black.  You can have tri colour on a tiny bit of the dog (usually around the tail) but it doesn't make a difference anyway... both parents have to be tricolour for all the pups to be tri, but as it's recessive one parent can be black and white, or brown/red and white etc... I think the OP was questioning the amount of white, not tri colour and this is dependent on white factoring in the parents... they don't have to show this white, they may carry it... one of my bitches is white factored, but has quite a white face, white collar and four paws, her sister (with a whiter face) mated with white factored dog produced cow like broken coloured pups... my own, mated with very little white dog, produced one with a white face and one with almost no white.... but all tri as the sire was tri....

Yes, that's what I was wondering - Phoebe has considerably more white on her than Holly.  If it's possible then it's a very good chance they are full sisters!  How exciting :-)

It was interesting talking to Holly's owners about her and Phoebe yesterday - they actually knew her in her first home as they lived in the same close, so I've had some more insights.  Interestingly though, they've had pretty much all the same issues with Holly, with car travel issues (she used to shriek constantly), the barking, a bit of noise reactivity - the only difference is that they sought help when she was less than a year old so things were sorted out in time.  Whereas poor Phoebe was left in an uber stressful environment, with only one other trainer (who was a choke chain moron), for 4.5 years :-(  So while Holly is now more or less fine, Phoebe is a mess and will likely never be the dog she could have been.  I don't expect I'll ever get her in the car, for example.  They are a great example of how important the right experiences and training early on is!

Thanks all :-)