Hi,
VLAN1 and BVI1 are different topics! The Management VLAN is always the "native" VLAN. So you can assign the VLAN xy to be the native VLAN and the Interface BVI1 is assigned to VLAN xy. Be aware of the native VLAN! It's submitted untagged.
!
interface BVI1
ip address 10.10.10.10 255.255.255.0
!
interface FastEthernet0.xy
description WLAN Management
encapsulation dot1Q xy native
!
The native VLAN is even a issue for DHCP. The builtin DHCP server only serves DHCP broadcasts within the native VLAN.
Kind regards
Peter