bash - AWK print group of lines twice if conditions met

I am having difficulties writing an AWK statement that would print out a group of lines twice under specified conditions, with the option to change values in the lines being repeated. For example, if the first field of a row is 11 ($1=11), then I would like to print out that row and the row that follows twice (adjusting the value in the second column ($2).

So far this is what I have, but it does not replicate lines with the first field = to 11 and the following line.

awk '{if(NF<3) print $0; if(NF==3 && $1==11) print $0, 1, 20; if(NF==3 && $1 != 11) print $0, 0, 0; if(NF>3) print $0;}'

Example Input

1 3

            6 0.1 99 
              0.100 0.110 0.111 
            7 0.4 88 
              0.200 0.220 0.222
           11 0.5 77
              0.300 0.330 0.333 
2 2
            7 0.3 66
              0.400 0.440 0.444 
           11 0.7 55

              0.500 0.550 0.555  

This is a simplified version of what I would like to do, so let's just say for simplicity I would like the printed NR where $1==11 and following row (NR+1) to have the value in the second column ($2) be half of the original value. Example, for the grouping of rows under the 1 3 section, the value after 11 is 0.5. Ideally, the rows printed out would have the value following 11 to be 0.25.

Ideal Output

1 3
                6 0.1 99 0 0
                  0.100 0.110 0.111 

                7 0.4 88 0 0
                  0.200 0.220 0.222
               11 0.25 77 1 20
                  0.300 0.330 0.333 
               11 0.25 77 1 20 
                  0.300 0.330 0.333 
2 2
                7 0.3 66 0 0
                  0.400 0.440 0.444 
               11 0.35 55 1 20

                  0.500 0.550 0.555  
               11 0.35 55 1 20
                  0.500 0.550 0.555  

Answer

With GNU awk for gensub() and \s/\S:

$ awk '$1==11{$0=gensub(/^(\s+\S+\s+)\S+/,"\\1"$2/2,1); c=2; s=$0} {print} c&&!--c{print s ORS $0}' file
1 3
            6 0.1 99

              0.100 0.110 0.111
            7 0.4 88
              0.200 0.220 0.222
           11 0.25 77
              0.300 0.330 0.333
           11 0.25 77
              0.300 0.330 0.333
2 2
            7 0.3 66
              0.400 0.440 0.444

           11 0.35 55
              0.500 0.550 0.555
           11 0.35 55
              0.500 0.550 0.555