LSMW recording - fund reservation with multiple item lines

It's my first time in this great forum, so... Hi all !

I need help to import fund reservation documents (tables KBLK, KBLP...) using LSMW.

I didn't find any BAPI or standard BI, so I decided to use a custom recording (transaction FMX1).

What I've done is to set header data, set a single position data and finally to save document.

Questions:

1. Do you know any BAPI, std. BI, or anything else concerning fund reservation creation that can be linked to LSMW ?

2. Using custom recordings, how can I handle an arbitrary number of lines ?

I really appreciate any suggestion.

Greetings. Manuel

PS: sorry for my english !!!