Quote from owlbear89 >>

((I think this would be for the first round of combat.))

The Orcs are still far enough away from you that you could choose to disengage and lead them on a merry chase without combat being initiated, which is why the flexibility, but yes, it does indeed look like combat will be starting in short order based on the parties' decisions.

(For when the orcs get about halfway:)

Meira moves just enough to get to where she has a good line-of-sight to fire her shortbow.  If she can, she picks not the closest target to her, but one towards the middle of the group headed in Gareth and Eldrin's direction. 
(Shortbow Attack: 19, Damage: 9 piercing + 7 sneak attack) 

She then pulls back a bit, trying to hide just behind the cellar entrance. (Stealth: 23)

Gareth, 

Your second arrow flies over the Orc packs heads as they continue to bear down upon you and Eldrin.

Eldrin begins forming the words of magic to cast magic missile at the lead Orc. Three motes of energy shoot out, impacting the Orc and causing massive damage, but it still keeps coming. 

Combat Begins:

Initiative order:

Surprise Round:

• Lyra 20
• Zephyros 13 Your bolt sinks into the Orc in the back of the pack. He stumbles and shrieks out in pain looking back towards the farmhouse.
• Meira 8 Your arrow hits an Orc in the middle of the pack in the back of the head. It falls to the ground, dead. Four other Orcs turn back to the farmhouse to see where the arrow came from, but they don't see anyone as you disappear from view. 

Round Two:

• Gareth 22
• Lyra 20
• Eldrin 13
• Zephyros 13
• Orcs 11
• Big Al 10
• Meira 8

(Surprise round)

From her hiding spot, Lyra calls upon Tymora's hand. The familiar slender, traslucent arm appears just behind the nearest orc. It hovers, poised to smack him on the nape—but waits until the fight truly begins to do it. Bam! (ooc: but sadly, that is a miss! Tymora's rolled a 7 to hit)

(Round 2)

This time, Lyra fires a beam of divine energy at one of the orcs farther from her (perhaps one of the unhurt orcs rushing toward Gareth or Eldrin?). The orc suddenly begins to glow as the cleric's divine magic marks him, making him an especially easy target! 

Action: Guiding Bolt 19 to hit / 12 damage. Whoever attacks this orc should get advantage.
Bonus action: Assuming there's an orc within 20 feet of Lyra (who stays for now near the farmhouse door—leaning out to cast her spells, then pulling back to stay partly hidden), Tymora's hand floats over to him and delivers a slap: 16 to hit / 8 damage
Special: Concentrating on Pass Without Trace (so, Stealth rolls from those close to Lyra still get a +10)

Ironheart reloads another bolt into his crossbow and fires it at the same orc as before. When the orcs get closer, his plan is to rush them like a madman, wielding his trident overhead.

Attack 10

Damage 4

Lyra,

You summon your spiritual weapon. Tymora reaches out to slap the same orc Zephyros previously hit with a bolt, but he proves too elusive for the blow as he ducks just in time. You send a bolt of divine energy hurling through the orc pack. It slams into the back of an orc just behind the lead orc and does massive damage. He's looking pretty hurt but is still able to maintain his footing. Tymora reaches out a second time to slap the same orc upside the head and this time connects. His head is batted clean off and rolls across the battlefield. The rest of his body falls to the ground, still twitching.

Gareth knocks another arrow and sends it at the lead orc. This time, his arrow connects, piecing the heart of the orc and sending him to the ground. Skidding to a halt. 

Attack 14

Damage 8

Eldrin sees the lead orc fall and the one right behind him illuminated by Lyra's spell. He sends a bolt of fire at this foe and burns a hole right through him. The orc falls dead, still smoldering.

Attack 23

Damage 9

The orcs seem undeterred by their fallen comrades and continue their pursuit of Gareth and Eldrin. However, a few of them do peel off to address the threat from behind. Three orcs continue forward, and three orcs return to the farmhouse. They move with shocking speed as they close the gap in both directions with only 10 feet left between them and both group of adventurers. 

[[OOC: Orcs used dash and their aggressive bonus action trait to close the distance.]]

Big Al waits as requested behind Zephyros, but it's clear the man is ready to engage. He peeks past the adventurers and asks, "Where's the rest of em? There was twice as many b'fore. Least 14 er so."

Meira,

You're up! Then we return to the top of round three.