maltese mix and issues

Question
I have a maltese mix. He is mainly maltese with a hair of poodle I would assume. He will be 2 in July. I have had him for a year. He has done ok with potty training but if I take him over to my family member's house he almost reverts back and will mark his territory in the house. In addition to this issue he has had a few instances of submissive urination. Pople bend over to pet him and he acts like he's in trouble, when he isn't and he leaks. I live alone with the dog and I have never had an instance of submissive urination. Its like he has issues if we are in a new place.

Answer
This is very common as he is a small dog, with what to him seems like giants in a threatening position.  I would use a belly band with him as this will help the marking and keep any submissive urination issues from making a mess.  Since he is ok at your house, and marks only at others, the belly band will cause him discomfort when he urinates as it will keep the urine in-similar concept to a diaper.

With the submission, make sure people do not approach him. Ask them to squat down and allow him to approach when he is comfortable.  As he experiences more people with less threatening behavior his confidence will increase.