How to customize Infopath Forms for SharePoint ?

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InfoPath

SharePoint2010

Hi Friends,

I am having a List with 6 columns.
say
a1
a2
a3
a4
a5
a6

Usually, On clicking ADD NEW ITEM, We used to get info path form for adding these values one by one like :
Enter value of a1 : [""""""""""""]
Enter value of a2 : [""""""""""""]
Enter value of a3 : [""""""""""""]
Enter value of a4 : [""""""""""""]
Enter value of a5 : [""""""""""""]
Enter value of a6 : [""""""""""""]


But i want now to ask the user like below:
Enter value of a1 : [""""""""""""]
Enter value of a2,a3,a4 : [""""""""""""] [""""""""""""] [""""""""""""]
Enter value of a5,a6 : [""""""""""""] [""""""""""""]


How can i do this easily in SHAREPOINT 2010 ?

Thanks a lot for your advice in advance.

Regards,
Nibin