OK, now we are getting somewhere.
First of all, several of your previous posts have mentioned changing your original visitor visa to a joining family resident visa. As you have already exchanged your original visitor visa with a work resident visa, your original visa is completely irrelevant. What you want to do is to exchange your current work RESIDENT visa for a joining family resident visa.
Now, let’s take this one step at a time:
First off is to get married. (Your original post said you weren’t married yet, not sure if that has changed.) To be legally married in Taiwan you will need to be recorded in your wife’s household registration. For a local marriage you will need a marriage certificate, a singles certificate, your wife’s ID and her chop. The singles certificate is usually something you can obtain from your local trade/representative office and all it needs to say is that as far as your native country knows you are single and eligible to marry (this and any other documents will need to be translated if they are not in Chinese or English). Get all these items and take your wife to her local household registration office to register your marriage. When that is done, get several copies of her household registration printout showing your name as a foreign spouse in the comments section.
Then you will need to get the joining family resident visa from BOCA. To prove a local marriage you will need the marriage certificate and household registration. The marriage certificate does not need to be authenticated by an overseas mission if the marriage was local. You will need to get a document from your home country proving you do not have a criminal record and that must be authenticated by Taiwan’s representative office in your home country. However, it is possible in many cases to do this by mail or have someone back home do it for you. You also need a health certificate, just as you did with your original ARC. Once you have all those items, go in to apply.
Once you get your new resident visa, go to the foreign affairs police to get a new ARC. You will need your new resident visa, marriage certificate, and your wife’s household registration to apply.
It really should be that simple. A “Type A” resident visa means it was issued for the purposes of work or investment. If you are not a blue-collar worker there is nothing preventing one from applying for a new resident visa inside Taiwan. In general the only types of visas that do not allow you to apply for new visas within Taiwan are non-extendable visitor visas. If they ask you what visa you used to enter Taiwan, say you entered on a resident visa. Technically when you were issued the resident visa inside Taiwan, it is counted as entering on a resident visa.
Now I’m going to be a bit blunt since you didn’t pick up on other’s trying to say this gently: You have a communication problem. Several of us have had trouble understanding what you are talking about in this discussion. I can only imagine how it must be for someone who doesn’t speak English well to understand what you are asking.
Your wife is your best resource here. She can discuss everything clearly in Chinese. She also will not face any subtle or not subtle discrimination that you may be facing. I understand that she is young and unsure of herself, but if she wants you to stay with her she’ll need to do some work to make it happen. If she really isn’t up to the task, how about another relative like your mother in law or father in law? How about a coworker? While I am often able to handle these things by myself, when I encounter obstacles I almost always find that once I get someone local to help me, the problems suddenly disappear, or an acceptable alternative is presented.
When you get the answer you want, don’t mess it up by bringing up other issues. The Taichung office said no problem until you said the Taipei office said otherwise. That made them second guess everything.
In any case, start the process. Start collecting the necessary documents. When you have what is needed, go in and apply. Don’t mention any irrelevant things. Just tell them, “Here are the documents their form requires; please process them.” Any additional information or comments just complicates things. Stick to the basics.
This really is something that lots of us have done without leaving Taiwan. It really does work. If you are being told different it’s probably because you aren’t asking the right people, aren’t asking the right qustions, or aren’t communicating effectively.