Update
I just wanted to give everyone following this thread an update.
1.) The lump sum garnishment order that DCSS placed AFTER the non-custodial parent was approved for SSDI was processed in time to enforce garnishment from his SSDI back pay. However, I want to stress that I believe it was only because the SSA had not yet calculated or processed his back pay. So, my advice to those that are owed arrears is, get in touch with your local Child support enforcement office and request a lump sum garnishment order be placed for the arrears owed. I'm not saying they will (even though they should), I'm just saying it doesn't hurt to ask.
2.) I also received the back pay for the children's insurance benefit's two days after the mother of the other two children turned in all of the required paperwork. However, it took her a week to receive the back pay. I believe I received mine sooner because they already had all of my information. So get to your local SSA office asap and give them what they need. Birth Cert's (for the child or children), visitation order (showing percentage of time), direct deposit info, yours and your child's SSN, and your DL or ID card.
3.) The morning I received the children's insurance benefit's back pay, I went to DCSS and reported it. It was deducted from the arrears owed. There is still a small amount of arrears owed (his back pay wasn't enough to cover all of it) which will be payed at $28 a month until paid in full. My child will receive $59 a month from the children's insurance benefit's which replaces child support. Because of his income now, the child support would be set at $47 a month and since $59 a month is more, that's what I'll get.
These are things that I questioned during this process so I wanted to get the info out there. If you have any other questions don't hesitate to ask, I can only answer according to my own experience though. Please do not assume that this is how it will turn out for you or anyone you know. Every situation is different. However, I want to express that if at any point your child support case is going to be closed (especially if you have an upcoming court date), call them everyday until they agree to keep it open. If you do not have an upcoming court hearing for child support and this is happening, file for one asap or contact the ombudsmen. My case was going to be closed and I pushed and pushed and pushed until they agreed that it should not have been set to close in the first place due to my upcoming court hearing. I believe the non-custodial parent's attorney (for whatever reason) turned something in that prompted closer and had I not fought for them to re-open it, I likely would have lost the arrears owed. Good luck to you all! Our children deserve financial support from both parents!