XG Active-Passive HA and LAG Ports

Hi There,

I'm configuring 2 x XG 450 devices in HA as Active-Passive, the HA is configured to monitor a 2 port LAG (LACP) to our Core switch.

Our Core switch is in a bonded configuration (ie, there are two disparate devices that are managed and appear as a single switch), our aim with the Sophos HA is to be able to weather the loss of one of the XG's without too much downtime.

What I'm unsure about, is whether all 4 ports on the core switch end should be configured in the same lag group, or should the primary and secondary XG ports be configured to separate lag groups?

Current Configuration:
Primary > Port A1 > LAG (XG_TO_CORE) > Core Switch Port ge.1.1 (LAG.0.1)
Primary > Port A2 > LAG (XG_TO_CORE) > Core Switch Port ge.1.2 (LAG.0.1)
Auxillary > Port A1 > LAG (XG_TO_CORE) > Core Switch Port ge.13.1 (LAG.0.2)
Auxillary > Port A2 > LAG (XG_TO_CORE) > Core Switch Port ge.13.2 (LAG.0.2)

Should it instead be:
Primary > Port A1 > LAG (XG_TO_CORE) > Core Switch Port ge.1.1 (LAG.0.1)
Primary > Port A2 > LAG (XG_TO_CORE) > Core Switch Port ge.1.2 (LAG.0.1)
Auxillary > Port A1 > LAG (XG_TO_CORE) > Core Switch Port ge.13.1 (LAG.0.1)
Auxillary > Port A2 > LAG (XG_TO_CORE) > Core Switch Port ge.13.2 (LAG.0.1)
...so that all 4 lag ports are in the same lag group?

The HA documentation diagram shows each physical port going to different switches (I assume using spanning tree etc), it doesn't touch on how LAG ports are / should be configured when HA is involved. I haven't gone any further with the configuration at this stage, I'd like to know that I've got this right before I go too much further.

Thanks in advance.

Brendan