>> using the same rules[ex:+abcd and +%28abcd%29], 
>> a relative link as: a href="?open=abcd"
>> is properly scanned and recorded. But a relative link as:
>> a href="?open=%28abcd%29" is not recorded.

I don't understand all the above. But it looks like the relative link is using
percent-encoding. Indeed, percent-encoding is commonly used by urls. To
translate, for example, %28 becomes the ascii char for 28-hex (=40 in
decimal), which is "(". And similarly, %29 becomes ")". 

Such that if you rewrite your httrack rule +%28abcd%29 as +(abcd) , then it
might work properly. Httrack doesn't seem to automatically recognize
percent-encoding in any options or urls that you pass to it.

<https://en.wikipedia.org/wiki/Percent-encoding>