crm2013: give some defaultvalues to the connected instance by clicking on a lookup in form

Hi all,

i have 5 lookups on my form.
I want to creat a new instance from every of the 5 buttons, but ...
give for each lookup a value to the new created instance, so that in the new creating instace knows from wich lookup it came, and with his info, set a value of an optionset.

This is, because the user knows, why he clicked an that one from the 5 possible lookups.
But standardly, the new opend form for the new instance asks the user to set that value. This is not really intelligent.

So - How can i give one (or more) values by clicking on the new lookup in the form,
and set this values in the new created data?

THX, Greets Pit