Transfer from HTB ISA to LISA or can I have two ISA?

Hi all,

I'm not sure where to post this, so apologies if this is the wrong place. I have a HTB ISA which I've been paying into for a while now, around £5,800 added in. However, I was hoping to buy a property much sooner and would have gone for the LISA if I had known. My situation now is I'm likely to buy now around September 2019, but wondered if it might be better to open a LISA and wait 12 months (so Jan 2020) to buy somewhere.

My question is, would I be able to use the contributed funds from both ISAs? I understand the bonus' would only be added from one ISA and after completion but is it still possible to use both to contribute towards the mortgage deposit? I could transfer over £4000 as a lump sum but would be missing out on the £1800 which I've put in?

Thanks

Bob