buddylist conditional on Postbit_Legacy

[Tane]

OK, I have seen some threads on this, but all relate to older VB versions.

I want a condition in Postbit_Legacy based on whether the poster is in your buddylist.

I am trying to get something that works with 3.6.

Previous threads:
https://vborg.vbsupport.ru/showthread.php?t=82471

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My problem is where to put this code:

// set-up for buddylist conditional - postbit
$isbuddy = explode(' ', $bbuserinfo['buddylist']);

if (in_array($post['userid'], $isbuddy))
{
$isbuddy = true;
}
else
{
$isbuddy = false;
}

From plugin at hook "postbit_display_start" - I don't seem to have access to $bbuserinfo['buddylist'] - I have also tried $vbulletin->userinfo['buddylist'].

From the Postbit_Legacy template, I CAN display $bbuserinfo[buddylist] - which a space separated list, not an array.

Any ideas, as I'm sure there is a simple answer that I'm missing.