They are both somewhat unusual and somewhat contradictory.
there (as an adverb of place) is associated with things that are at some distance from the speaker (in contrast to
here).
this and
these are associated with things that are near the speaker (in contrast to
that and
those).
There are this boy and this girl says
In that position at a distance from me are the boy near me and the girl near me.
That doesn't make a lot of sense.
![Smile [:)]](/emoticons/emotion-1.gif)
How about
That boy and that girl are there or
This boy and this girl are here ??? I think these are better.
_________
there (as the adverb of existence) is only used with indefinite determiners in the typical cases. The demonstratives
this, that, these, and
those just don't go with
there
(of existence) except in special circumstances not operative in the
examples we are discussing here. Moreover, an expression of
location is often used with
there (of existence).
There are a boy and a girl next to the car.
There are some ducks in the pond.
There is a boy at the door. There is a duck on the lawn.
CJ