I suggest to create the form for sending malware through the website.Is this possible?
I would say it is entirely possible and something which has been mentioned a number of times, but no action to date, so currently not possible.
Most of these requests however were when there was no other option than emailing the sample to avast. Then avast 4.8 had the ability to upload files from the virus chest (on the next update check), though if this was for undetected malware you had to manually add it to the User Files section of the chest.