Re: How to notify FDA of change of ownership ?
Welcome to the Cove 
The procedure is the same as mentioned in the thread - first AA Limited will transfer the owner/operator to BB LImited and then the BB Limited will take the devices under thier organization.
Rerfer - TRANSFER OF OWNERSHIP OF A 510(k) - http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm150086.htm#5k
A 510(k) may be bought, sold, or transferred. FDA is not involved in transfers of ownership. The new owner should maintain information documenting the transfer of ownership of a 510(k), including any legal transactions that took place, in its 510(k) files.
The new owner should list the device according to 21 CFR part 807 and the previous owner should delete its device listing. Upon inspection of the firm or upon entry of glove shipments into the U.S., FDA may request a review of documentation of ownership. If the owner is not able to provide the information, FDA may request the owner to submit a 510(k). You may not distribute the gloves until FDA clears the new submission.
Note that neither a registration nor a listing proves 510(k) ownership. The new owner of the 510(k) should maintain files with documentation proving ownership of the 510(k).
To avoid problems when importing a device with a transferred 510(k) ownership, FDA recommends that a copy of the specific information relating to the ownership sale or transfer accompany all shipments to the United States. This could be a simple one-page document detailing the transfer transaction.
Regarding a change of ownership, our situation is a little different. The registered company (i.e., AA Ltd.) who has initially registered the devices (510k) was purchased by another company (i.e., BB Ltd.). How can I change the ownership of the registered devices? Should I open a new establishment for BB ltd.? and then connect the new establishment to listing of these devices?
I'll appreciate your reply.
I'll appreciate your reply.

The procedure is the same as mentioned in the thread - first AA Limited will transfer the owner/operator to BB LImited and then the BB Limited will take the devices under thier organization.
Rerfer - TRANSFER OF OWNERSHIP OF A 510(k) - http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm150086.htm#5k
A 510(k) may be bought, sold, or transferred. FDA is not involved in transfers of ownership. The new owner should maintain information documenting the transfer of ownership of a 510(k), including any legal transactions that took place, in its 510(k) files.
The new owner should list the device according to 21 CFR part 807 and the previous owner should delete its device listing. Upon inspection of the firm or upon entry of glove shipments into the U.S., FDA may request a review of documentation of ownership. If the owner is not able to provide the information, FDA may request the owner to submit a 510(k). You may not distribute the gloves until FDA clears the new submission.
Note that neither a registration nor a listing proves 510(k) ownership. The new owner of the 510(k) should maintain files with documentation proving ownership of the 510(k).
To avoid problems when importing a device with a transferred 510(k) ownership, FDA recommends that a copy of the specific information relating to the ownership sale or transfer accompany all shipments to the United States. This could be a simple one-page document detailing the transfer transaction.