Debian Programming :: HTML Export - Consolidate Several Lines Of CSV File With Firewall Rules

I have a CSV file, which I created using an HTML export from a Check Point firewall policy. Each rule is represented as several lines, in some cases. That occurs when a rule has several address sources, destinations or services.

I need the output to have each rule described in only one line. It's easy to distinguish when each rule begins. In the first column, there's the rule ID, which is a number.

Here's an example. In green are marked the strings that should be moved:

See example. The strings that should be moved are in bold:

NO.;NAME;SOURCE;DESTINATION;SERVICE;ACTION;
1;;fwgcluster;mcast_vrrp;vrrp;accept;
;;;;igmp;;
2;Testing;fwgcluster;fwgcluster;FireWall;accept;
;;fwmgmpe;fwmgmpe;ssh;;
;;fwmgm;fwmgm;;;

What I need ,explained in pseudo code, is this:

Read the first column of the next line. If there's a number:

Evaluate the first column of the next line. If there's no number there, concatenate (separating with a comma) the strings in the columns of this line with the last one and eliminate the text in the current one

The output should be something like this. The strings in bold are the ones that were moved:

NO.;NAME;SOURCE;DESTINATION;SERVICE;ACTION;
1;;fwgcluster;mcast_vrrp;vrrp-igmp;accept;
;;;;;;
2;Testing;fwgcluster-fwmgmpe-fwmgm;fwgcluster-fwmgmpe-fwmgm;FireWall-ssh;accept;
;;;;;;

The empty lines are there only to be more clear, I don't actually need them.