I'm not an rtf expert - all I usually do is create a small sample document
and try to work out what chunks you need to achieve a particular effect.
Doing that suggests that what you need is to finish each section with:

last bit of text in the section \sect }

then start the new section with e.g.

\sectd \linex0\endnhere\sectdefaultcl
or
\sbkodd\linex0\endnhere\sectdefaultcl
etc. depending on the section break type. Then, if you have a new header in
the new section, have a header block, such as

{\header \pard\plain \s15\ql
\li0\ri0\widctlpar\tqc\tx4153\tqr\tx8306\nooverflow\faroman\rin0\lin0\itap0
\fs20\lang2057\langfe1033\cgrid\langnp2057\langfenp1033 {s1 header
\par }}

If you have a new footer in the new section, have a new footer block along
similar lines.

Then get straight into the body of the new section, e.g. my experiment has:

\pard\plain \ql \li0\ri0\widctlpar\nooverflow\faroman\rin0\lin0\itap0
\fs20\lang2057\langfe1033\cgrid\langnp2057\langfenp1033
{first bit of text in the new section...