Mohan, to my understanding, all the three i.e. along with, together with, and as well as have similar treatment in grammar.
With the presence of either of these in a sentence, the verb takes colour from the subject like in the initial example -
Eric along with Emiley is going for a walk, here '
is' is used because
Eric is
singular. Instead of 'along with' even if ' together with' or 'as well as' was used in the sentence, we would have used 'is'.
Only 'and' in a sentence is capable of combining the subject and making it plural.
Hope this helps !
Kyle, please correct me in case there's any disconnect.