What you have described seems more an empathic link than anything else. But don't worry, there IS hope!
The empathic process can be broken down into three main stages: (1) input; (2) emotional response; and (3) physical sensation/effect. There is a
very small interval between stages, especially between (2) and (3). If the sensitive does not isolate the source of initial input, the emotional
response and subsequent physical reaction(s) are likely to overwhelm any further attempts to pinpoint the entry point.
Since your wife is familiar with the person overwhelming her, she needs to separate her own thoughts and feelings from those of the other person(s).
A good way to do this is to go somewhere where she feels secure, and do whatever works to ground & calm herself. Meditation, chanting, just listening
to music, etc. If she's having problems clearing her mind and finding her center, I recommend meditating with soft white noise (fan, radio off
channel, etc.) in the background. This will give her subconscious something on which to focus, thereby stopping it from constantly chiming in.
Once she has reached a point of as close to absolute stillness of self, then she can start paying attention to the empathic process. Reach out to one
family member, keeping close track of what's going on (I recommend taking notes). Merge with his/her emotions, stop when that person's feelings
start to become her own, and return to self. Try this with different persons. Finding the point where the input/emotional reaction/physical response
chain begins is important, as you can then stop it before it begins.
Another benefit of this exercise is that by controlled "visits", you can become acquainted with each person's emotional thumbprint and thus
recognize it if they begin sending you spontaneous input. In time, your inner defenses will begin to react if the input threatens to become
overwhelming, preventing clouding of any information received by leaked emotion and physical response. Eventually you will be able to control the
link enough to probe any input received for information concerning why the person is broadcasting to you.
In case anyone's wondering, I recently had a friend who was sending me daily panic attacks, and had to work out what was going on for
Hope this helps, and I'm available for any questions.