Very interesting legal question. I am not an advocate but quickly read upon the applicable judgments to give you my two cents:
The interim order passed in your case is, by definition, not a final order in itself and therefore whether it is appealable is itself not very clear. In fact, the few Supreme Court judgments I read indicate otherwise. Of course, your advocate will persuade you to file an appeal for obvious reasons - he gets his fees - either way - whether you lose or win. The most important strategy in law is to keep the litigation simple. Filing an appeal when your FINAL rights are not compromized in any way is nothing short of complicating your litigation with no reciprocal returns.
What you should focus on is the final maintenance Order. In fact, if you get a final Order which entitles you to more maintenance, then you can ask for retroactive enhancement on the interim maintenance that was already paid to you. So, why file an appeal now? If the final order is NOT what you believe you are entitled to, then file an appeal. It will be a final order in the legal sense and therefore an unquestionably appealable Order. If you prevail in the appeal, then you get retroactive adjustments.
Remember that interim orders are granted before a trial is completed. While some interim orders may have the form of a final relief, interim maintenance does not fall in that category because after a full trial, you will be granted maintenance based upon ALL facts before the Court which facts are not before the Court now. So what are you going to appeal against? The High Court will itself not have all the facts to modify the interim maintenance order.
This is a purely legal opinion and has nothing to do with the merits of your case - maintenance is a complicated subject and unless all parameters are known, it is difficult to comment. You certainly need a good advocate to pursue maintenance and an advocate who is encouraging you to file an appeal on interim maintenance may not be the right one...
