Thanks for the advice/tips everyone.
I posted on a couple other sites and received some good information as well.
Seems the weeping tile coming into that upper drain may in fact be a weeper from my foundation, window wells or footings?
Common when my house was built, supposedly?
With no dedicated primer lines going to this drain, I am likely going to re-route my furnace/AC condensate line to this drain to help keep it primed.
From what I understand and since this drain is in our laundry room, this is dedicated drain in case of a hose breakage, flood and like previous mentioned, for outside weepers when the ground gets saturated?
I am going to fill up the wash basin shortly with hot water and listen real close when I drain it to ensure nothing drains to this spot, however. Most are saying not likely but some say there is a possibility?
2 additional things I was told. Products exist, like a one way check valve that will stop the odors coming up these drains and another was to use Murphy's Oil Soap instead of vegetable oil to keep the P trap from drying out.
Thanks for the info, everyone, I appreciate it very much!