They're both lovely plants in the right setting but I, like your DH, wouldn't want them in my garden. They wouldn't, "fit" as I have a very, "English country garden" cottage type garden. I wouldn't even want them in pots to be honest.
It's really hard when someone gives you display items for your home that, "don't fit" but you can't shove a shrub in the cupboard and remember to take it out when the giver visits!
Does your DH do all the gardening and does your DSis know this? If so, it's her faux pas so no need to feel embarassed and she shouldn't react sensitively.
I think the best thing is to come clean and explain that, whilst you're very grateful for her generosity, they won't fit in with your garden.
I think you need to know someone really well before you buy them display items for home and garden and being related is often not enough.
If someone in the family does me a favour and I want to buy them a gift I'm really blunt, "now you're having a present whether you like it or not and my budget is £x so give me a choice of three items so I can," surprise" you with something I know you'll really like or we'll both risk being awfully disappointed" ?