That's how the Paint Bucket tool is supposed to work. It's meant to be able to fill an enclosed area which is not enclosed by a single path.
If you don't want a new path created, you'll need to use a traditional fill. For the traditional fill to work, you need a single closed path. So if the enclosed area that you want to fill is not already created by a single path, you'll need to create a single path. (That's why the Paint Bucket tool is so convenient, in certain circumstances.)
If you can show us an example, or even the SVG file, I could explain using your drawing as an example. If you can't share it, let me know and I'll work up an example to show you.
If you want to extend the previous path (e.g. for creating one shape that fills two areas with the same colour) you can fill the first then hold shift as you fill the second (and subsequent) area. But I've done a lot of filling of comics with this tool, and to be honest it's often easier to just create the paths separately then select them and use Path > Union afterwards.
One other thing to note: as the title of the topic mentions 'layers' I wonder if you're coming from a bitmap graphic mindset, and considering each object to be a layer. Layers and objects are different things, and it's normal for a single layer to contain many, many objects. You don't necessarily need to create a single object unless you have a specific requirement that demands it.
Beginners' Questions Paint bucket fill creating new layers
Inkscape.org
When I use the paint bucket to fill my object, it creates a new object everytime I click it. How do I fill without it creating a new object?
Welcome to the forum!
That's how the Paint Bucket tool is supposed to work. It's meant to be able to fill an enclosed area which is not enclosed by a single path.
If you don't want a new path created, you'll need to use a traditional fill. For the traditional fill to work, you need a single closed path. So if the enclosed area that you want to fill is not already created by a single path, you'll need to create a single path. (That's why the Paint Bucket tool is so convenient, in certain circumstances.)
If you can show us an example, or even the SVG file, I could explain using your drawing as an example. If you can't share it, let me know and I'll work up an example to show you.
Or else here's what the manual has to say about that tool: http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Bucket.html
If you want to extend the previous path (e.g. for creating one shape that fills two areas with the same colour) you can fill the first then hold shift as you fill the second (and subsequent) area. But I've done a lot of filling of comics with this tool, and to be honest it's often easier to just create the paths separately then select them and use Path > Union afterwards.
One other thing to note: as the title of the topic mentions 'layers' I wonder if you're coming from a bitmap graphic mindset, and considering each object to be a layer. Layers and objects are different things, and it's normal for a single layer to contain many, many objects. You don't necessarily need to create a single object unless you have a specific requirement that demands it.