Is there a way to implement such a backup scheme?
If you want to run daily incremental backups, your configuration might look like the following.
1. On the Schedule Option step of the backup plan wizard, select the Recurring (Incremental) option and click edit. Check days from Monday through Friday, pick the time, frequency and save
2. On the same step, check the "Execute full backup" box, pick Sunday, define frequency and save.
3a. If you want to keep increments for generations (full+increments) on the "Retention Policy" step, select the "keep backup for" option and set it to 3 weeks.
3b. In case you want to keep increments only for the latest generation, set "Keep backup for" to 1 week and check the "Enable GFS" box, then enable the "Period for keeping weekly backups" option and set it to 3 weeks.
I hope that helps