Questions with multiple sigs for a specific house

Let me elaborate.

I want to ask a question that involves 2 persons that would be signified by one house - my brother and cousin (3rd). How does one read a chart like this? Who would get the primacy for the house and how would the other person be signified in that case?

You can try assigning them to planets that match their characteristics. Ex. Saturn, older, Mars, younger.

You can also use triplicity rulers of the house

Your brother is 3rd. Your cousin is your parent's sibling's child (5th from 3rd from either 4th/father or 10th/mother). So, cousin from father's side is 10th, cousin from mother's side is 4th.

When the regular means of investigation fails, turn to astrology.

I've given much thought to the situation so this should be a valid question. The question, "Is my cousin tormenting my brother?" The long and short of it is that we've been down this road before, and I want to handle this situation better than I did the last time. (Let's just say I was very martial in my manners that time). But before I decide on a course of action, I want to know if there is anything to my suspicion. My cousin is very wily and street wise and he would have had his past experience with me to inform him on how to proceed (if he was interested to do so again.)

Using both methods suggested by Bun and Cap (thanks folks):

Bun: 3rd house is Aries. Brother is Mars in Taurus (My brother has a Taurus stellium so this fits). Jupiter is fire trip ruler in the night and Jupiter is placed in the 8th house and unconnected to Mars. Both in Venusian signs (just a coincidence to me)

Verdict: No conflict

Cap: Woopee kayay...both house 3 and house 10 happens to be ruled by Mars. The water trip ruler for night is Mars (dorothean). Mars is already in use so I'll go with Venus. Venus is in Aries (my cousin could definitely be described as an Arian character) it's Rx and partile to Mercury in the 2nd house. No aspect with Mars. In this case both planets are in each others signs so they in fact find each other pretty cool

Verdict: No conflict

So things seems to be on the up and up.But I would like some other opinions if you're willing.

You can also do “are rumors true”

And now, based off of that, the "rumour" would be true.

I'm holding out for other interpretations but for his sake it better not be true.

Using the Magic 8 Ball astro-divination technique, quesited house is the 3rd house (for both brother and cousin since in the 8 Ball divination we don't use planetary significators but only the specific quesited house itself)...Aries is the sign on the 3rd whole sign house...Aries = Mars, and according to the 8 Ball rules, the answer to this question is: NO

Alright, so that's about 3 No's to 1 Yes (and another illustrious astrologer gave her opinion privately, another No)

I should rest easy then, as at this point I'm probably looking for trouble if I pursue this any further.

Thanks again folks, I've learned a good deal from this exercise.