How do I add a new HDD to encrypted RAID5 array?

[ghostcorps]

Hi Guys,

 This seems liek a really basic question, I expect a simple 'no', but I havn't found anything definative yet.

 I currently have a hardware RAID5 array (onboard using Intel Matrix) encrypted with GELI, but I need to add 2 new discs to the array. If I add a disc to the array and have it rebuilt with the Intel Matrix Storage Manager, prior to booting FreeBSD will that destroy the encrypted data?

 If so, how can I decrypt the disk without copying the data to another partition?

Using:
OS: FreeBSD 7.0
Mobo: Asus p5b-e http://www.asus.com.au/products.aspx?l1=3&l2=11&l3=307&l4=0&model=1347&modelmenu=1
HDDs: Seagate 500g SATA2

Please let me know if you need any other info.

Thanks
=^_^=