Surely it is adjustment problems.
I'm an old fashioned guy and would want to convey at least displease on the inside poop, best if caught in the act.
Most dogs, I believe, respond better to reward than punishment, some hold a grudge I fear.
Have you considered getting one of the portable fences? I have one that makes a "cage", more a "play pen".... and two such sections would be large enough for a small do go have room to poop and do with the absence of a leash.
Or recently departed Westie didn't care much for being on a leash, but that didn't prevent him from his interest in doing a drop..seems being in a new place stimulated that in him. He could have a complete toilet exercise in the yard, but when taken for a walk in "town" he always had to poop on the sidewalk. Maybe he just like to put me in my place ;)
Good luck, and hope you had a good Christmas, and many happy New Years with your new puppy.
I would not worry too much about the eating situation and put him on a schedule. Try feeding twice a day. Use the same area you want him to eat in whether it be near the other dog or not, depending on the eating dynamics. Put the food down for 15 - 20 mins, whether he eats or not, pick it up and put down again later on, AM and PM. Hopefully, he will get the idea and eat. As for the pot tying issue, especially if he had a yard he could freely go into before, it may be the leash and you being close by. Is there a possibility you can leave the stool from your other dog out for a day or two or do you have to clean up right away? If you can leave it out, he may get the idea that is where he can go. Instead of a short leash, you could try a lunge line or long piece of like clothesline, securely fastened to his collar so he can move around some away from you. I might mention, you want to make sure he is on a collar he cannot slip out of. Good luck and please update.
good news, he has not had an accident today and he pooped two times outside! also he ate half of his food in the morning and tonight he ate all his supper. we have an old fence we used to use for our old dog we had about 6 years ago, so I might try putting that in the backyard if he continues to have problems. we have a pretty long leash too. i am not too worried anymore he is doing great today and right now he is cuddling and about ready for his bed :) thank you for the help!
Great news. A lot of changes for him. Dogs cAn be such creatures of habit. Sounds like he us feeling more comfortable and hope he will be a nice addition to your household.
Thanks for the update.