First off, why don't you create schema like this:

members: id, name
events: id, name
event_member (pivot table): id, member_id, event_id, number

Then simple relations:

// Member model
public function events()
{
  return $this->belongsToMany('Event')->withPivot('number');
}

// Event model
public function members()
{
  return $this->belongsToMany('Member')->withPivot('number');
}

Now you can access what you need as easily as this:

$member = Member::find($memberId);

$event = $member->events()->find($eventId);

$number = $event->pivot->number;

Same the other way around.

You can eager load the relations and access number on all of the loaded models

Thank you Jarek, for a well made answer.

Actually I saw this coming =) The thing is this is a very simplified version of the problem. The tables are more crowded and one can exist without the other, they are seperated for schematic and permissional purposes.

In this context; I found this approach useful when dealing with non standard Laravel eloquent relations:

// eager load my standard relations.
$myModel->load(array('relation1','relation2');
// set manual relation for my custom relation load.
$myModel->setRelation('custom_relation', $myModel->myCustomRelationFunction());

That way you can continue to rely on standard Eloquent functionality even when dealing with non standard relations.

Good tip Flightfreak. Haven't seen the 'setRelation' function before, I'll check it =)