yes i see the reason why people try to cheat the governement of tax, this was explained to me already when i spotted the irregularity.
one lawyer told me i could use the tax fraud against my ex, while another told me to forget it as only the seller would be troubled by extra tax demands, not my ex. so i'm not exactly filled with confidence about lawyers here, some obviously don't know the law themselves.
it seems i'm wasting my time searching for advice here as nobody has experience of this themselves or they are not members of this forum if they have. thanks to those who made an effort.