The first thing that you need to know, Lavania, is whether your brother-in-law ever signed up for the SBP (Survivor Benefit Program.) If he did, then your sister, and possibly her son also, depending on his age, should be receiving monthly payments. The amount she wold receive would, I believe, be anywhere from $300 to the full amount of his retired pay, depending on the amount of coverage that your BIL selected when he signed up for the program. If he never signed up for coverage under SBP, then, unfortunately, I don't believe that she will get anything at all since retired pay stops automatically on the death of the retiree. If he had signed up for SBP, then DFAS (Defense Finance and Accounting Service) should have, upon receipt of notification of her husbands death, sent her a letter outlining what she needed to do to start her SBP payment. Of course, the letter may have never been sent, never been received or lost in the shuffle during the stressful time of his passing away. When I read your question, I did a little searching and found two links that should provide you/her with some information/guidance on this matter. Try looking at
http://www.military.com/benefits/survivor-benefits/survivor-... for some frequently asked questions and answers on the SBP program or look at
http://www.military.com/benefits/survivor-benefits/the-survi... for more info on the SBP plan.
I hope this helps.
Tom