Help with Lady whose getting to big for her boots!!

[AngelaMya]

Hey all
I’m new and looking for advice on my German Sheppard cross Collie girl who is 10 months old.
Mya is a fab friend and is perfect with me and my eldest daughter (we both walk her) she will listen, respond and be generally well behaved for her age. But we are being to encounter jealously issues which I need to nip in the bud before they become a problem.
As well as Mya we have a small elderly cross and over the past few weeks Mya has begun to try and dominate her to want of a better word steer her into walking where Mya wants and more worryingly sometimes snarls at her. I have been blocking Myas view from the other dog and telling her no and I have also starting making sure that our smaller dog is fed first as she is higher in the pack than Mya, I hope this is the right thing to do!
Now for our second problem, which is probably my fault. Mya is very, very attached to me (mainly as I do all the feeding, grooming, training etc) but she recently has started getting really upset if my other daughter or husband comes near me (not all the time but enough to course worry). She will whine and try to push them away from me and get in there first so to speak, this I have tried to remedy by pushing her away until I’m ready for her to have attention, hopefully again I on the right track. I just really would appreciate any advice of how to deal with Mya’s new behaviour as I don’t want an unruly spoilt dog, she is going to be a big girl and the last thing I want is for her to ruined by me allowing or ignoring this behaviour. Thanks for reading xx