Both SDA and ODG drawings are supported in OpenOffice.org Draw, so it is probably the best option to convert SDA drawings to ODG format. Might also be possible using online conversion services like PrimoOnline or ZAMZAR.
Convert OpenOffice.org drawing file to OpenDocument drawing.
We have found 2 software records in our database eligible for .sda to .odg file format conversion.
Multiplatform software - convert sda to odg on any platform
Graphic editor for diagrams and simple graphics from OpenOffice.org suite
Convert from sda file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned sda to odg. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Graphic and diagram software from LibreOffice suite