Backing on a horse at SP, then laying on it at In-Play

This has been taken from a support ticket:

I am looking at trying to automate the following;

1. Look at specific horses in specific races
2. Back them for say €50 at SP
3. Lay them in-running for €100 at exactly half of SP.

Let's review it step by step.

1. Look at specific horses in specific races

To select specific races, just add them from the event tree or use the Market Locator.

There is a number of ways to choose the horses you want to bet on.
You can either import them from a text file. See the manual's chapter "Auto-Trading - Import selections for auto-trading".
Or you can tick them manually upon switching the market in Full Mode (if you don't feel like creating a simple text file, but why wouldn't you?).
Or you can put any of the horses' parameters into a text file, let's say their stall number, and then feed that file to a trigger condition in this manner:

Selection's Stall Number is in file [file_path]

It can't be anything - name, ID, index etc.

In the attached trigger all bets are placed on selections with Rank = 1 (i.e. the favourite). This is a placeholder condition, remove it if needed and add your own.

2. Back them for say €50 at SP

Betting at SP is a special operation on BetFair, not the same as placing a regular bet. There are several triggers action for that, among them "lay at SP" and "back at SP", the latter is used in the attached trigger file. Pay attention to the fact that once your SP bet is placed, it can't be cancelled or its size modified.

3. Lay them in-running for €100 at exactly half of SP.

Once the market turns In-Play, it is no longer possible to "back at SP" or "lay at SP". Instead, you can place a normal lay bet at a price equal to the starting price. There is a special variable for that in MarketFeeder Pro, actual_sp.
Please note that it is not possible to bet at a price lower than 1.01. Therefore, the lowest possible price that the first trigger can back on will be 1.01*divisor. This price is set as the price limit for the SP bet. If this bet does not get matched, the laying trigger will not fire.

The sizes of the bets and the divisor applied to the lay price can be conveniently set and amended in the Constants section of the file.