Publish customized/forked component library under LGPL

[fiddlingAround]

Hi Everyone,

I am not a professional developer, but I like experimenting with different technologies.
After doing some scripting in Python I came to Qt for a small amateur project.

My project is a library of GUI components based on the source of the discontinued library "Symbian Components" by Nokia.
https://qt.gitorious.org/qt-components/qt-components/source/7d9bf82a089a60429e279d26dc305d34386b7295:src/symbian

I cloned the repository and started to customize most of the components and made them work with Qt5. Some of the source files remained untouched.
May I call it a fork? There are some other sources, too.
In the distant future I would like to publish this derivative work under the LGPL so other people can use my components to create GUIs.

Currently my project is mixture of differently licenced sources.
Only some selected examples:
Symbian Components by Nokia, discontinued
Button.qml, License: BSD
https://qt.gitorious.org/qt-components/qt-components/source/7d9bf82a089a60429e279d26dc305d34386b7295:src/symbian/Button.qml
SDeclarativeImageProvider, License: BSD
https://qt.gitorious.org/qt-components/qt-components/source/7d9bf82a089a60429e279d26dc305d34386b7295:src/symbian/sdeclarativeimageprovider.cpp

Qt Quick Components by Digia
QQuickRangeModel, License: LGPL/GPL
https://qt.gitorious.org/qt/qtquickcontrols/source/5483ccd3547dcb3edbe4c50d70e6921ee5c5cb7a:src/controls/Private/qquickrangemodel_p.h
QQuickFolderListModel, License: LGPL/GPL
https://qt.gitorious.org/qt/qtdeclarative/source/3d96c688a919c3ebc0ea3822e59bbc728c68eb95:src/imports/folderlistmodel/qquickfolderlistmodel.h

Ubuntu UI Toolkit by Canonical Ltd.
QuickUtils, License: LGPL/GPL
https://bazaar.launchpad.net/~ubuntu-sdk-team/ubuntu-ui-toolkit/trunk/view/head:/modules/Ubuntu/Components/plugin/quickutils.cpp

I copied miscellaneous features into my project, because it is not possible to ensure their availability on all platforms out-of-the-box and without installing additional dependencies.

To cut a long story short:
Is it possible to "relicence" my customized "mixture" under LGPL? What do I have to consider before release? What should the ?new? licence headers look like in my source files?
I found a similar question in the forums, which refers to discontinued parts of the Qt framework itself and not projects using Qt.
"Licensing for discontinued Qt Solutions projects"
http://qt-project.org/forums/viewthread/3983

Thanks in advance

Tobias
fiddling around

PS: I love Qt very much and appreciate the outstanding work on it! Keep on rocking!