The most important thing is that you communicate right now.
From the HQ perspective they make a lot of money with very few developers and all seems to be going well, with no problems at all. Judging by the spreadsheets this looks great!
Your task is now to explain to them the risks involved with proceeding forward. You can also present them a plan to mitigate that risk without interrupting ongoing operations too much and slap some money figure on it — ideally you present them three options where one of those is doing nothing. Be aware that the decision on this is not yours, it is theirs. Your task is to tell them everything relevant for that decision. You can also tell them, that your professional opinion is that this is something that ahould have been done years ago and the fact that this didn't explode in their faces yet was pure luck. But again it is their decision.
How you lay it out depends on you, but there have been many tips already. Version control might be the first thing. Maybe you can present it as: one day a week goes towards maintenance or something.
As an aside this helps to cover your own behind if nothing is done and everything goes south in a year. Then you can point to that extensive risk analysis you presented them with and tell them you told them so.
From the HQ perspective they make a lot of money with very few developers and all seems to be going well, with no problems at all. Judging by the spreadsheets this looks great!
Your task is now to explain to them the risks involved with proceeding forward. You can also present them a plan to mitigate that risk without interrupting ongoing operations too much and slap some money figure on it — ideally you present them three options where one of those is doing nothing. Be aware that the decision on this is not yours, it is theirs. Your task is to tell them everything relevant for that decision. You can also tell them, that your professional opinion is that this is something that ahould have been done years ago and the fact that this didn't explode in their faces yet was pure luck. But again it is their decision.
How you lay it out depends on you, but there have been many tips already. Version control might be the first thing. Maybe you can present it as: one day a week goes towards maintenance or something.
As an aside this helps to cover your own behind if nothing is done and everything goes south in a year. Then you can point to that extensive risk analysis you presented them with and tell them you told them so.