Sorry to see your theatre was broken into Kathy!
Lets face it no matter what your insurance coverage you still loose out anyway!
I remember the last time we were done over, at the Old Mill Theatre in South Perth.
It was 7 PM on a week night, I opened the theatre & went in thru the FOH, in the dark to backstage to turn on the lights. The cast of ?Chorus Line? followed me in.
As I was walking back thru the auditorium, a stranger rushed pass me carrying a large suitcase saying "excuse me, excuse me? while attempting to push the cast to get to the front door.
I shouted out to the cast members to stop him, they just stood there with their mouths open, so stupid ran & rugby tackled him to the ground outside the door. The bloke dropped the case & kept shouting for his mates to help him. While I was struggling to subdue him, I kept asking for some one to help. All they did was stand in a circle & gawk at me!
A vehicle drove up & two bods jumped out. I thought good help at last! They rushed up knocking the cast out of the way & grabbed me, I was too busy protesting they had the wrong bloke, until I was bodily thrown over a near by hedge. They scarped with the culprit & jumped into the waiting car & were off like a dirty shirt.
Although most of the electronic gear was recovered. We found there was a heap of other equipment such as tools, headsets & various other bits & pieces, had been stolen anyway.
I was verbally abused  by a  young Blue Heeler, that attended the breakin from the Police  Station opposite the theatre. Until I advised him that being a retired Justice, I did not need advice or warrant a homily from an apprentice constable, for me to realise I was a total numbat, in trying to stop a robbery, I realise that I was an idiot!!
However I was rightly or wrongly admonished further by the theatre board, for a lost opportunity for them in making a larger claim to the Insurance Company!  
So as a reluctant hero, I became a castigated zero in less than a heart beat.
Needless to say when I finished ?A Chorus line? I pulled the pin & have never directed there any more!
Also the theatre group has yet to get any pay out for their claim with the Insurance Company, because they could not prove ownership or give any serial numbers of the equipment stolen.
I believe they still link  me as the main reason, why they have not been paid!
So when I started up the Phoenix Theatre here in the City of Cockburn. I made use of the Councils free security service available. They send a bloke who invisibly marks all the equipment & valuables worth over $100. There is a digital photo taken of each piece along with it?s serial number. He then puts it on a lap top & burns two discs, one of them is to keep in the safety of another location, in case of fire. He also takes interior pics of the premises as well, along with supplying warning stickers that all goods on the premises are indelibly marked. These stickers are displayed visibly on the inside of exterior windows.
Also he wipes all details from the lap tap after he has produced the discs & leaves forms so you can list the property & update it with information of future equipment. You can have this service repeated at no cost on a regular annual basis.
But besides all the above - the moral of the story is to ensure you have plenty of proof &/or an inventory of equipment with it?s $ value. Also try * get a New for Old replacement insurance coverage, which defiantly helps, & never interfere with a robbery in progress!
As this is a great justification for the group to pay the cost of having insurance in the first place!
I hope you can get full recovery Kathy!