how to merge contiguous blast hsps! (-m 8 tab)

Hi, guys!

I performed blastx (-m 8) using a query file of many sequences, and for each target sequence, the output contains many fragmental hsps of significance, and these hsps have overlap positions or not.

so, how can i merge those closely related hsps into one via setting a flanking value (e.g <300bp) when these hsps match the same subject (different regions).

In the following figure, I want to transform the upper results to the lower ones

http://www.imagebam.com/image/0c13b2256142668

Thanks in advance!

Transform

scaffold16:1661-2239(+)       gi|471236998|ref|YP_007641386.1|  50.00  122  52  3  **225  578**  603  719  2e-53   126                   
scaffold16:1661-2239(+)       gi|471236998|ref|YP_007641386.1|  75.00  76   19  0  **1    228**  528  603  2e-53   108
scaffold16:1661-2239(+)       gi|333951646|gb|AEG25349.1|       52.10  119  54  2  **225  578**  604  720  7e-53   124
scaffold16:1661-2239(+)       gi|333951646|gb|AEG25349.1|       77.63  76   17  0  **1    228**  529  604  7e-53   109
scaffold28:2776872-2777385(-) gi|327335359|gb|AEA49877.1|       70.18  57   17  0  **173  343**  554  610  3e-30   90.5
scaffold28:2776872-2777385(-) gi|327335359|gb|AEA49877.1|       72.22  54   15  0  **1    162**  497  550  3e-30   67.0

To

scaffold16:1661-2239(+)       gi|471236998|ref|YP_007641386.1|   .      .    .  .  **1    578**   .    .   2e-53   **234**
scaffold16:1661-2239(+)       gi|333951646|gb|AEG25349.1|        .      .    .  .  **1    578**   .    .   7e-53   **233**
scaffold28:2776872-2777385(-) gi|327335359|gb|AEA49877.1|        .      .    .  .  **1    343**   .    .   3e-30   **157.0**