Hi,
1st Query:-
You have to do the posting correctly. I think claim has to post to both part to FI because current month you have to recover the previous month amount but you dont have that amount to payment side. So for that rean it's required to post for two side in FI like as a example of Er PF contribution.
2nd Query:-
If employee is full month absence or leave the organization mid of the month then also LWF has to deduct and pay to LWF department. So if current month employee has not received any amount then as a claim it will go to next month for recover to that amount.
Regards,
Sankarsan