Growing Raid 1 (but reducing disks)

Hi,
I have:

Raid 0 MD2 |--------------5Tb---------------|
on
Raid 1 MD0 |----2Tb---|
Raid 1 MD1 |-------3Tb--------|

MD0 = sde, sdf (2Tb each)

MD1 = sdc, sdd (3Tb each)

I want to migrate the Raid 0 MD2 volume data onto a 10Tb raid 1.

sda, sdb (10Tb each)

Can I achieve this using the raid rebuild tools so that I end up with:

Raid 1 MD0 |--------------------------10Tb----------------------|

MD0 = sda, sdb (10Tb Each)

MD1 = (gone)

MD2 = (gone)

, or would it be necessary to create a new raid1 and then rsync the Raid 0 MD2 volume to it.

Raid 1 MD3 |--------------------------10Tb----------------------|
rsync ^

Raid 0 MD2 |--------------5Tb---------------|

Does that make sense?