planing to book a KLM flight from AMS to MAN to connect in MAN a SQ flight ( seperate Ticket ). Does KLM check our luggage through to final destination SQ ?
KL 1073 AMS 07:50 Amsterdam 1S 25M DIREKT 08:15 MAN Manchester
SQ 51 MAN 11:40 Manchester 13S 00M DIREKT 07:40 +1 SIN Singapur
I know, we have enogh time to pick up and check in again, but for some reason I not want to check in with SQ in MAN again.

Do KL and SQ interline? Of course they do.
Will KL check your bag to SQ on a separate ticket ? Be prepare for not. You may succeed but I would say that there are greater chances that they won't. So plan accordingly to have time to claim bags and go landside for checking-in with SQ.

Unless anything has changed lately, KLM use T3 at MAN and SQ use T2 which is quite a long walk.

KLM and SQ interline on some flights to Australia and New Zealand.

Interlining is meant for single tickets, where travel on both airlines is booked in a single transaction.

You should NOT assume that either airline will transfer bags for you when you are travelling on separate tickets.

You should allow sufficient time between tickets to account for delays to your flight, having to retrieve your bags at your intermediate destination, including the possibility of delayed baggage delivery and even baggage loss, requiring you to remain even longer in order to file a missing baggage report.

My advice to you would be to get to your intermediate destination the night before your longhaul departure from that point. If you miss your second ticket, then you have absolutely no protection and will either have to abandon your travel plans, or shell out for a new ticket for immediate departure which will be far more expensive than any savings you originally had realised by booking travel in this way.

Thank's for your input.
I want to avoid to check in with SQ in MAN under all circumstances.
If not KLM, I would try Brussel air ex BRU or LH ex FRA-
Only this 3 airlines have a flight ( sundays ) morning that early,

You cannot avoid checking in with SQ; KLM will be unable to check you in or issue a boarding pass.

Can you explain why you want to avoid checking in with SQ? Do you mean you wish to avoid having to go landside/enter the UK (and again, if so - why?)?

Why not book the entire flight with SQ. they use Flybe to get you to MAN under full codeshare, you go through the transfer lounge at MAN and then airside bus transfer from T3 to T2. Also having it on one ticket means extra protections like rebooking if connection is missed too.

I can not book the itin in one, because the MAN-SIN.......... is already issued some month ago.
And no Flybe does not check through onto any other airline ! I already did this last year via DUS-BHX, and them told me in DUS them generally not check through.....
However i simply want to avoid to go landside in UK. BP's are not the problem! I can print out them during OLCI and bring for KL/Brusselair/LH or whoever check us through. KL ex AMS is the cheapest cost less than 70 Euro, Brussels aprox 95 and LH around 110 ( all i think + luggage )