it took the belgian embassy about four months to decide on the application. however, to be able to apply, you have to make all your travel arrangements. they didn't anticipate the process to take this long, had to first move, and then cancel their arrangements altogether. in the end, the application got rejected, but the official reasons were cryptic. my friend's interpretation was that the embassy was concerned that his parents might not return to india. they had the option to appeal, which can take 6 to 12 months. chances of appealing successfully are low and so are the chances of getting a visa in a renewed application. in the process, they lost about €3000, which is a lot of money in rupees.
instead of appealing, the parents booked a vacation in the netherlands. the visa application went through in less than a month. they got a schengen visa, meaning that they could also visit belgium. and this is how his parents visited him in the end.
his conclusion was that belgian bureaucracy is out of hand and that the EU has interesting loopholes.