Sewer cost for two plots (A+B)

Following question:

There are two undeveloped plots and a street with a partially installed sewer for wastewater.

Neither plot is connected to the sewer yet.

The street passes by a developed plot connected to the sewer, then continues past plot A and then past plot B.

Only plot B wants to build. Who bears the costs here? Only B or also A with possibly the developed plots that are also connected to the sewer.

What happens with the costs if plot A wants to build later. The sewer should then already be in the street.

What is the legal situation?

Typically, channel connection fees are not calculated based on the effort within public streets but rather on something like property size and a municipal calculation formula miracle.

That means, actually neither a nor b pays the actual effort.

An exception to this are private streets or when it is an outer area.

However, this can be different locally. It depends on the specific sewage statute.

Is it generally the case that everyone has to share the costs proportionally, regardless of whether they have been connected for decades and now an extension for new houses is planned.

It is not a private road but a public street of the city.

Not the outer area but Paragraph 34 Baugesetzbuch, so within the district.